EzekielRaiden
Follower of the Way
For my own answer to the question, as I have said before, I think 5e is missing somewhere between six and twelve classes (and I favor the higher end). That would allow us to more neatly focus each class. With a set of, say, 4-6 total subclasses for each class, we can have enough depth for folks who really love to tinker, and enough accessibility for folks who just want something straightforward.
The Wizard as it existed in 5.0 would become all one subclass: the Specialist archetype, with each school specialty having its own power. (Perhaps presented on a table?) Other Wizard types would have other focuses that have nothing to do with spell school, and everything to do with the academic study of magic. Cleric domains would be relatively condensed, but as a result, punchier; I suspect Life, War, Light, Shadow (Trickery/Twilight), and then maybe something more archetypal, perhaps Luck and Order. (Note, these are opposing pairs; this is intentional.) With the option of a Swordmage class, there's no longer a need for the Fighter to carry the Eldritch Knight weight, and its archetypes can be more focused on being as good of a Fighter as it can be; likewise, there'll be no need for a Bladesinger Wizard. (Warlock would remain as the build-it-yourself class for those who want that kind of experience.)
By having a larger number of classes, a bunch of specific archetypes can be given full-throated, clear support, some of which clearly very much need that, hence the seventeen different ways to make "person who uses magic and also a weapon". An infinite number of classes isn't achievable, and even publishing 25 all in a single book is probably beyond the limits of a single book. So, publish the first (say) 13 in a single book, and then publish three new classes each in the next three books, along with a slow drip of new "archetypes" for each.
Expand feats--slightly. Perhaps one every three levels instead of every four--and for God's sake decouple them from stats! Perhaps start them at 2nd level, so you get your 7th and final regular feat at 20; that's just two more than 5e baseline, which is what 5e Fighters already get (naturally, redesigns would need to account for any power shifts like this). Keep them chunky and useful--avoid chains longer than at absolute most 3 feats, and those 3 feats better be some of the best-written feats ever made by human hands, and I don't mean "powerful", I mean "good-quality", as in, worth taking and also cool/neat/flavorful/fun. Definitely make sure absolutely all feats get very close eyes on at the editing stage--while it's unavoidable that some feats will be weaker than others, that's just how math works, have people on staff who review this stuff to avoid the "wow this feat is...almost total trash" problem. It was an issue in 3e, 4e, and 5e--let's not make it a fourth consecutive edition where a third of all feats are kinda $#!+.
De-spell-ify the game. Actively. Reduce spell lists whenever possible. Make absolutely every spell justify its existence. That doesn't mean "remove all weird/quirky spells"--it means don't include a spell just because it could maybe be present. Spell bloat is an enormous but often overlooked problem in 5e. Personally, I'd go back to the spells vs rituals distinction from 4e, but if that isn't in the cards, then at least avoid having more than (say) two dozen or MAYBE three dozen total spells at any given spell level (for reference, there are sixty-four 1st level spells ALONE in 5.5e! It doesn't drop below 40 until you reach sixth level spells!!!), and make spell lists (where possible) more distinct from one another. Spells are a huge huge huge space of character customization bloat where a ton of them are just...they aren't useful, they don't do anything, they don't even add worldbuilding. The ceremony spell is neat to read on the page, but it's not even something you'd actually have NPC spellcasters use!
So: 13 classes (e.g. add Warlord to the 5e baseline of 12), with a slow drip of additional new classes across the edition's lifetime to add spice and interest. Players usually love new classes, as long as they're reasonable and doing something neat, and getting only a few every year or two means it's always important when a new one arrives. Subclasses can be added only slowly, judiciously, when we understand how all of the existing ones tick (and can fix any errors in how we made them the first time around). Feats are boosted just a smidge compared to 5e baseline, getting just a smidge more over 20 levels and still being chunky and strong, but allowing for limited (and again I stress limited) chains, with a VERY sharp eye for weak, unnecessary, or just badly-made feats. Likewise, trim the spell list significantly, even if it requires painful sacrifices--spells are bloating out of control here, almost as bad as feats in 4e.
The Wizard as it existed in 5.0 would become all one subclass: the Specialist archetype, with each school specialty having its own power. (Perhaps presented on a table?) Other Wizard types would have other focuses that have nothing to do with spell school, and everything to do with the academic study of magic. Cleric domains would be relatively condensed, but as a result, punchier; I suspect Life, War, Light, Shadow (Trickery/Twilight), and then maybe something more archetypal, perhaps Luck and Order. (Note, these are opposing pairs; this is intentional.) With the option of a Swordmage class, there's no longer a need for the Fighter to carry the Eldritch Knight weight, and its archetypes can be more focused on being as good of a Fighter as it can be; likewise, there'll be no need for a Bladesinger Wizard. (Warlock would remain as the build-it-yourself class for those who want that kind of experience.)
By having a larger number of classes, a bunch of specific archetypes can be given full-throated, clear support, some of which clearly very much need that, hence the seventeen different ways to make "person who uses magic and also a weapon". An infinite number of classes isn't achievable, and even publishing 25 all in a single book is probably beyond the limits of a single book. So, publish the first (say) 13 in a single book, and then publish three new classes each in the next three books, along with a slow drip of new "archetypes" for each.
Expand feats--slightly. Perhaps one every three levels instead of every four--and for God's sake decouple them from stats! Perhaps start them at 2nd level, so you get your 7th and final regular feat at 20; that's just two more than 5e baseline, which is what 5e Fighters already get (naturally, redesigns would need to account for any power shifts like this). Keep them chunky and useful--avoid chains longer than at absolute most 3 feats, and those 3 feats better be some of the best-written feats ever made by human hands, and I don't mean "powerful", I mean "good-quality", as in, worth taking and also cool/neat/flavorful/fun. Definitely make sure absolutely all feats get very close eyes on at the editing stage--while it's unavoidable that some feats will be weaker than others, that's just how math works, have people on staff who review this stuff to avoid the "wow this feat is...almost total trash" problem. It was an issue in 3e, 4e, and 5e--let's not make it a fourth consecutive edition where a third of all feats are kinda $#!+.
De-spell-ify the game. Actively. Reduce spell lists whenever possible. Make absolutely every spell justify its existence. That doesn't mean "remove all weird/quirky spells"--it means don't include a spell just because it could maybe be present. Spell bloat is an enormous but often overlooked problem in 5e. Personally, I'd go back to the spells vs rituals distinction from 4e, but if that isn't in the cards, then at least avoid having more than (say) two dozen or MAYBE three dozen total spells at any given spell level (for reference, there are sixty-four 1st level spells ALONE in 5.5e! It doesn't drop below 40 until you reach sixth level spells!!!), and make spell lists (where possible) more distinct from one another. Spells are a huge huge huge space of character customization bloat where a ton of them are just...they aren't useful, they don't do anything, they don't even add worldbuilding. The ceremony spell is neat to read on the page, but it's not even something you'd actually have NPC spellcasters use!
So: 13 classes (e.g. add Warlord to the 5e baseline of 12), with a slow drip of additional new classes across the edition's lifetime to add spice and interest. Players usually love new classes, as long as they're reasonable and doing something neat, and getting only a few every year or two means it's always important when a new one arrives. Subclasses can be added only slowly, judiciously, when we understand how all of the existing ones tick (and can fix any errors in how we made them the first time around). Feats are boosted just a smidge compared to 5e baseline, getting just a smidge more over 20 levels and still being chunky and strong, but allowing for limited (and again I stress limited) chains, with a VERY sharp eye for weak, unnecessary, or just badly-made feats. Likewise, trim the spell list significantly, even if it requires painful sacrifices--spells are bloating out of control here, almost as bad as feats in 4e.
