ggaemo has already declared and the decisions will be finalized in May. My speculations for the rest of the class (and these are possibilities) are:
Midas - WeMade has tons of Terrans and BaBy's getting better. Coaches apparently have to sign a release to let a player join ACE, and it might be a good way for him to get more playing time.
NaDa - This guy's made at least 4 career comebacks already. Someone who made it into an MSL Ro8 a year ago has to have something to contribute.
NOT iloveoov - I don't think he practices as much as most progamers since he's coaching.
NOT Bisu - however, former SKT player GoRush said he wants him on.
LuCifer - He's 23 years old and was sort of good for a while, I just couldn't think of anyone else. Basically, expect Much to continue being ACE's main toss.
sAviOr - If EffOrt's slump continues then Hydra, MIsO, and Devil are ready to jump in. This is the only way he could play more games.
July - What's the weight requirement for joining the Air Force?