Remathilis
Legend
We've seen four classes now with subclass progression being standardized into 3rd, 6th, 10th, and 14th level from the otherwise scattered progression all over the place. We will assume all 12 PHB classes with keep a similar progression, though its worth noting they may not look exactly the same, if cleric domain is anything to go by. The purpose is to look at the rammifications of this change on the current subclasses in supplemental books.
Artificer
Current Progression: 3, 5, 9, 15.
So close! The current artificer is within one level of the new paradigm. Presumably, if the artificer gets redone, it will be adjusted to git the 3/6/10/14 model.
Barbarian
Current Progression: 3, 6, 10, 14
Beginner's Luck! The 2014 barbarian perfectly matches the new paradigm. That will mean most barbarian subclasses will work fine, accounting for the changes in the core class itself.
Bard
Current Progression: 3, 6, 14.
Our first snag. The bard utterly lacks a 10th level ability. Which means most bardic subclasses will need a new ability added at that level. In the interim, I guess a bonus feat would be stopgap for anyone looking to use a 2014 subclass in 1D&D.
Cleric
Current Progression: 1, 2, 6, 8, 17
Well the current UA shows us there is changes coming to clerics. We are already aware the change of domain has been moved to 3rd, and that the bonus proficiencies of domains have been moved to Divine Order. It also looks like the first level domain spells are gone. This will mean most domains will lose the bonus weapons/armor, proficiencies, or cantrips along with one line of spells. Channel divinity at 2nd is moved to 6th, divine strike is a base-class feature at 7th, the current 6th level feature is moved to 10th and the 17th level feature is dropped for 14. That should make most subs still work with cleric with minimal fuss, which is good because waiting on redesigns for nearly a dozen cleric domains seems like eternity.
Druid
Current Progression: 2, 6, 10, 14
With the exception of the odd choice of putting circle at 2nd along with wildshape, I don't see much problem delaying druid circle to 3rd. Most druid circles should work fine.
Fighter
Current Progression: 3, 7, 10, 15, 18
Hoo-boy. This one is going to need some work. We have one more feature than is available in 1D&D. That means at the very least the last two features would come at 14th level as a double-up. I hesitate to speculate until we see the 1D&D fighter, but I imagine there is going to be a lot of work needed to make old fighter's work.
Monk
Current Progression: 3, 6. 11, 17
Well, the first two features arrive right on schedule. The 11th will be one level sooner, the 17th 3 levels sooner. That should make those later level features more useable.
Paladin
Current Progression: 3, 7, 15, 20.
Another oh-boy. Luckily, we have the right about of features, but the drop of five levels for the 15th (down to 10) and the 20th capstone down to 14th might mess up some power levels. Bonus spells should be fine, as they already start getting them at the same starting level.
Ranger
Current Progression: 3, 7, 11, 15
Close enough that the UA ranger works fine with the existing subs. One level sooner on all features but the first won't ruin power-levels. Bonus spell rangers (mostly the Xanathar ones) might be worth keeping an eye on.
Rogue
Current Progression: 3, 9, 13, and 17
Another class that got their sub-features too late. Each of their class features will drop 3-4 levels. I don't wager that it shouldn't cause many problems though.
Sorcerer
Current Progression: 1, 6, 14, 18
I think the sorcerer will benefit greatly from the new design; most of their later sub features came way too late. Bloodline bouncing back to 3rd is interesting, and I truly wonder what they will do with the bonus spells later subs got. But overall, I think most subs will be just fine.
Warlock
Current Progression: 1, 6, 10, 14
Another class that most subs should work just fine it. The movement from 1st to 3rd level for Patrons might actually help eliminate the blight that is hexblade dips for sorcerer and paladin. The changes to bonus spells might be similar to cleric (losing 1st level) but the bigger questions will be how it interacts with any changes to pact magic. Overall though, seems most patrons will remain viable.
Wizard
Current progression: 2, 6, 10, 14
Another class that, save for its tradition moving up a level, will be just fine. Just in case you fear losing your transmuter subclass when WotC reduces the eight current subs down to four.
Obviously, we won't know exact details until we see the UAs for all the classes, and it will be interesting to see what subs get included in the PHB if the magic number is now four each. But I think that with two major outliers (fighter and bard) getting odd-numbered subclass features and sorcerer, paladin, and rogue getting their features at much lower levels than they did previously, most classes align or were pretty close with the new design numbers. That should mean most subclasses will remain usable in 1D&D. As always, time will tell.
Artificer
Current Progression: 3, 5, 9, 15.
So close! The current artificer is within one level of the new paradigm. Presumably, if the artificer gets redone, it will be adjusted to git the 3/6/10/14 model.
Barbarian
Current Progression: 3, 6, 10, 14
Beginner's Luck! The 2014 barbarian perfectly matches the new paradigm. That will mean most barbarian subclasses will work fine, accounting for the changes in the core class itself.
Bard
Current Progression: 3, 6, 14.
Our first snag. The bard utterly lacks a 10th level ability. Which means most bardic subclasses will need a new ability added at that level. In the interim, I guess a bonus feat would be stopgap for anyone looking to use a 2014 subclass in 1D&D.
Cleric
Current Progression: 1, 2, 6, 8, 17
Well the current UA shows us there is changes coming to clerics. We are already aware the change of domain has been moved to 3rd, and that the bonus proficiencies of domains have been moved to Divine Order. It also looks like the first level domain spells are gone. This will mean most domains will lose the bonus weapons/armor, proficiencies, or cantrips along with one line of spells. Channel divinity at 2nd is moved to 6th, divine strike is a base-class feature at 7th, the current 6th level feature is moved to 10th and the 17th level feature is dropped for 14. That should make most subs still work with cleric with minimal fuss, which is good because waiting on redesigns for nearly a dozen cleric domains seems like eternity.
Druid
Current Progression: 2, 6, 10, 14
With the exception of the odd choice of putting circle at 2nd along with wildshape, I don't see much problem delaying druid circle to 3rd. Most druid circles should work fine.
Fighter
Current Progression: 3, 7, 10, 15, 18
Hoo-boy. This one is going to need some work. We have one more feature than is available in 1D&D. That means at the very least the last two features would come at 14th level as a double-up. I hesitate to speculate until we see the 1D&D fighter, but I imagine there is going to be a lot of work needed to make old fighter's work.
Monk
Current Progression: 3, 6. 11, 17
Well, the first two features arrive right on schedule. The 11th will be one level sooner, the 17th 3 levels sooner. That should make those later level features more useable.
Paladin
Current Progression: 3, 7, 15, 20.
Another oh-boy. Luckily, we have the right about of features, but the drop of five levels for the 15th (down to 10) and the 20th capstone down to 14th might mess up some power levels. Bonus spells should be fine, as they already start getting them at the same starting level.
Ranger
Current Progression: 3, 7, 11, 15
Close enough that the UA ranger works fine with the existing subs. One level sooner on all features but the first won't ruin power-levels. Bonus spell rangers (mostly the Xanathar ones) might be worth keeping an eye on.
Rogue
Current Progression: 3, 9, 13, and 17
Another class that got their sub-features too late. Each of their class features will drop 3-4 levels. I don't wager that it shouldn't cause many problems though.
Sorcerer
Current Progression: 1, 6, 14, 18
I think the sorcerer will benefit greatly from the new design; most of their later sub features came way too late. Bloodline bouncing back to 3rd is interesting, and I truly wonder what they will do with the bonus spells later subs got. But overall, I think most subs will be just fine.
Warlock
Current Progression: 1, 6, 10, 14
Another class that most subs should work just fine it. The movement from 1st to 3rd level for Patrons might actually help eliminate the blight that is hexblade dips for sorcerer and paladin. The changes to bonus spells might be similar to cleric (losing 1st level) but the bigger questions will be how it interacts with any changes to pact magic. Overall though, seems most patrons will remain viable.
Wizard
Current progression: 2, 6, 10, 14
Another class that, save for its tradition moving up a level, will be just fine. Just in case you fear losing your transmuter subclass when WotC reduces the eight current subs down to four.
Obviously, we won't know exact details until we see the UAs for all the classes, and it will be interesting to see what subs get included in the PHB if the magic number is now four each. But I think that with two major outliers (fighter and bard) getting odd-numbered subclass features and sorcerer, paladin, and rogue getting their features at much lower levels than they did previously, most classes align or were pretty close with the new design numbers. That should mean most subclasses will remain usable in 1D&D. As always, time will tell.
