Either Flatzone will return and/or Mr. Game & Watch will return... I've been keeping up with the numbering system, which appears to be in order of being programmed in the series... It starts with the Original, then Melee, then Brawl... Here is it so far.
Smash Bros. = 1
Donkey Kong = 2
Starfox = 3
Kirby = 4
F-Zero = 5
Metroid = 6
Earthbound = 7
Pokemon = 8
Zelda = 9
Mario = 10
Yoshi = 11
Fire Emblem = 12
??? = 13
Ice Climber = 14
Animal Crossing = 15
Wario = 16
??? = 17
Kid Icarus = 18
Hmm, there is only one franchise that would be between Fire Emblem and Ice Climber... Game & Watch will return.
Oh, and now I think all the clones will return except maybe Pichu and Roy. We know both Link and Mario's moves and we can gleam that they have changed a bit. Mario sports the FLUDD as a Down+B, and Link's got redesigns and a modification of the Side+B move, so that it makes a minitornado now. So what would this tell us about clones based on them?
Luigi needs a new Down+B as well, and will likely get it with the Poultergust 3000 being so available. (Instead, of sending opponents away like the FLUDD, the Poultergust would suck opponents into Luigi's range) Luigi also needs a new Final Smash.
But Dr. Mario will ALSO need a new Down+B & Final Smash as well, which means Dr. Mario has the potential for having two moves unique to him and the modification that his Megavitamins have to Mario's Fireball.
Young Link if he appears in Brawl would obviously be based on Wind Waker... He'd keep his Fire Arrows, but also would have the Boomerang (Rather than the Gale Boomerang that makes the minitornade) and the Hookshot (Instead of the Clawshot), as well as having Fire Arrows, Cartoony Bombs, and the Spin Attack... He also could have an all-new Final Smash as well.
Dr. Mario & Young Link end up being declonified purely because Mario and Link have different effects and different moves now. I haven't seen all of Fox's and Pikachu's moves or any hint of Marth or Captain Falcon to judge on the cloneliness of Falco, Pichu, Roy, and Ganondorf, but I do have it from Mario & Link.