I foresee (hope) the following:

AST - Obviously, since it's moving to pure healer
SCH - I foresee SCH getting a big rework to fit with Sage. I suspect that Scholar and Astrologian will be the "buffing" healers (One shield, One "pure), hopefully SCH will get a bit more than just Chain Strategum. Maybe Aetherflow will be used for party/party member buffs and the heals connected to Aetherflow will just be cooldowns (something like that)
SMN - I feel like this is the perfect time to really sit down and "fix" SMN since they're already doing the SCH rework. I'd say if it doesn't happen now, it's not likely to happen.


What I think needs to be reworked:

All Healers - I don't really heal that often and play SCH whenever I do, but the DPS kit of healers needs to be way more complex than it is, and in normal content I rarely use half of the healing kit. I'd love to see some interplay with damage skills and healing skills (e.g. doing damage buffs your next heal). One of my favorite "healers" I ever played in an MMO was RIFT'S Chloromancer, you would put a buff on a party member and a percentage of any damage you dealt would heal that person. It would allow high skill players to sit there and heal less because they are doing a lot of damage, while those who don't want to stretch themselves can focus on simple DPS skills to boost their healing a little bit but spend most of their GCDs on heals.

BRD - Gotta figure out something with the DoTs and the party buffs. Right now, the DoTs just feel like a speed bump that you need to get through to start your rotation. (SMN "fixed" this problem with tridisaster basically making it so that DoT management isn't a thing if your rotation is good.) The songs don't really provide a significant amount of support (I feel like there's balance difficulty since buffs need to be useful in 4 man content but not overpowered in 8 man) and the personal DPS isn't great, especially considering the rotation.

All Ranged Physical- I think all of them need a pass to rebalance and determine an identity. I don't have examples for the other classes, but playing ranged physical DPS felt someone unfulfilling to me

MNK - I didn't play MNK really before the rework. From my point of view there seem to be a lot of abilities that are artifacts of the original design. It's certainly possible that they'll be more important once we hit 90. It's fun, but it feels like it's between designs right now, that the changes that were made were meant to be a stepping stone between what it was and what it will be.

DRK/WAR - I switched back and forth every 2-4 levels and leveled WAR and DRK at the same time and it made it pretty painfully obvious how the general gameplay was similar. Delirium and Inner Release are basically the same thing and I feel like they need to be looked at and given their own identities (Both Delirium and Inner Release followed by Bloodspiller and Fell Cleave bad design. I think they should be different).