That's an idea I've been bringing up quite a bit but no one seems to think its a valid option. Or at least, no one has commented on the possibility.
Capcom can't afford ****. Nintendo would NOT include Ryu unless they got something BIG in return. I'm thinking either Nintendo vs. Capcom game for Wii U, or Nintendo bought a Capcom IP--probably Mega Man--and Ryu is replacing the "Capcom" rep.
Okay, want to clear this up pretty quickly before theories get too thick in here, it's starting to make the Kremlings uncomfortable.
Nintendo is not buying out any IP, it is not their style. They currently now own the publishing rights to Bayonetta (but not the IP itself), but that is as far as Nintendo is going as of right now. Pretty sure it is due to the stance of their open door policy and them not actively seeking out existing IP, this goes without saying MM and Sonic both have a pretty rugged history Nintendo may not want to "redeem" in the near future.
However, knowing what I know, coupled with what has been openly discussed from Nintendo in the past years of Directs, Nintendo is collaborating with several third parties. Capcom is not excluded.
We know SEGA has an exclusive release roster for Nintendo and Sonic related games, Namco working on SSB4 and a new, unannounced RPG (and the Tekken U on launch), Koei with Hyrule Warriors and Atlus recently with FExSMT. Nintendo has also reached out to get exclusive content on their system with collaborations within these companies, such as Ubisoft and Mario costumes in Rayman Legends.
However, the one we have yet to see was Capcom (one of the original list not mentioned since). I do believe their collaboration may be big for us as gamers, and may be a reason Ryu may been considered in Smash. I suspect it is, indeed, Mega Man related however.