I will be very surprised if we don't at least get elementalist wizards and elemental domains for cleric in next year's Adventurer's Handbook. Probably others as well (Sha'ir for warlock and Elemental/Genie bloodline for Sorcerer are likely).
Other subclasses already mentioned I'd like to see:
- Barbarian: A barbarian that can turn into a bear (or another animal) when raging (Path of the Skinchanger?).
- Fighter: Cavalier/Knight, and some sort of dedicated Tank/Defender type.
- Paladin: Oath of Liberation/Freedom (CG).
- Rogue: Scout (i.e. non-magical, less fighty ranger).
- Warlock: Vestige, Spirits of the Dead, Dragon, and Celestial patrons.
- Wizard: Generalist, Defiler, Preserver, Chronomancer (needs many new spells, though).
- A Shaman, somehow (cleric or druid is the thematic choice, but warlock might work better mechanically - this may require a new class entirely).
Subclasses not mentioned I'd like to see:
- Barbarian: Something like Pathfinder's Bloodrager, a barbarian that can transform into things based on their bloodline. I also have a weird idea for a sort of Warlord/Barbarian hybrid, a barbarian leader that can "broadcast" rage to others - something like "Ragecaller", but needs a better name.
- Fighter: An unarmed-focused fighter (already done
here already, I see, and beautifully so).
- Paladin: Oath of Tyranny (LE), Oath of Slaughter (CE), Oath of Order (LN), Oath of Anarchy (CN), Oath of Protection (N, based on protecting a certain person, place, or thing).
- Sorcerer: A subclass that ISN'T a bloodline (like Wild Mage).
I was going to suggest an Investigator for Rogue (more "non-criminal rogue" than Pathfinder's alchemist hybrid) but that might be more a department for a custom background with the standard rogue/thief.
Also, a full class I'd like to see - something like "Inventor" or such, with 3E/4E's Artificer, 2E's Tinker, and Alchemist (Pathfinder-style) as subclasses. That won't be practical until we get guidelines for magic item creation, however.