I'm thinking, that if Megaman doesn't make the roster by the time the game is released, maybe Nintendo will continue to develop new content downloadable through Wi-Fi/LAN Connection. Maybe if by high demand (which he is) Megaman will be among the new content in the works or as a future release that can be downloaded. Kind of like in Mega Man Powered Up where you had to download Roll to obtain her.
More or less back on the subject, imagine adding the ideas and parts from his games into the Level Designer Mode. Imagine placing Vanish Blocks, Conveyer Belts, Instant Death Lasers (Quickman's level), Compressors (from Metalman's Stage) into you own levels? Not to mention all the sweet remixed tracks from various Megaman games. Metal Man, Flash Man, Wood Man, Crash Man and Wily Stage 1 would be definite yeses in my book. They would make great Smash tunes to say the least.
All in all, Mega Man is just to good a character to pass up for Brawl, for more reasons then just to have him with his own set of moves, fighting against other video games stars like Sonic and Mario like the video game icon that he is. His revelation would also innovate new elements to the game play, making Brawl an even bigger game then it already is.
I personally couldn't care less if X or Zero gets in. That's not to say I dislike them, heck, I love the X Series. But I think Classic Mega Man should be the top candidate. If Megaman.EXE or Star Force or whatever gets in in-place of the Classic, I will be very disappointed and, even in disarray. Of course, many people have suggested that the alternate forms of Megaman should be additional skins for Megaman. However, In doing, you also have to take the voices into consideration. I wouldn't want X sounding like the kiddy, childish Megaman we all know and love.
Cole Howard (voiced Mega Man in Powered Up) should be the voice of Classic Mega Man. Mark Gatha (Voiced Megaman X in Maverick Hunter X, Command Mission and X8) should stay the voice of X, as he does a perfect job of it. For Megaman Trigger, he needs a teenagery voice. Same goes for Megaman. EXE and Star Force Megaman, though not the super deep voice of Andrew Francis they used in NT Warrior. You know though, Maybe Cole Howard wouldn't sound too bad for them at all.