Seems like I'm the only one with any faith in Isaac.
To clear some things up, Camelot (the creators of golden sun, the game Isaac comes from), is still owned by Nintendo as a 2nd party, but are making an online golf game for the PC at the moment (considering these are the guys that made Mario golf, it's not too surprising). They've also announced that they are making an RPG, but nothing is known about it except that its in development.
Now to Isaac. Golden Sun was a popular GBA RPG game, and there's a chance that it might get some representation in Brawl. If it gets as much as a character, then Isaac is pretty much the best choice (Felix is also, but I think overall Isaac has priority, but that's just my personal take on it). He is a swordsman, but his psynergy skills could easily be implemented into his moveset to make him a unique character. He also appeared twice on Sakurai's poll, so it seems asd though Sakurai might take him into consideration. His problem though is that he comes from a currently unrepped series, and there are plenty of of other new series that are also deserving of representation, and part of me feels that Isaac may be pushed to the side.
I'll give him a 50% chance, as while he has a good chance he's nowhere near a certain edition.
Nominate: Lucario (x3), Krystal (x1) and Midna (x1)