I personally can't think of a reason why he would stay.Quick question. Do you think Snake would ever be cut for a different Konami Rep? I mean, I don't find him a shoo-in, but I don't think it's likely that he would be cut in favor of a different character from the same company.
now I know this is a crazy reason, but I don't see any character appearing in a previous version a surefire confirmation. and i don't see any character as important to nintendo's history a shoo-in. now that the game is more about cross promotion than before, and after the waiting and speculation before brawl that i endured, I count everyone as out until i see them in, save for the members of the original twelve who still have games coming out.
I recall reading an article saying that snake was supposed to be in melee. now i could be wrong as this may have been 5 or 7 years ago. but Kojima and Sakurai are friends, and Kojima asked him if Snake could be in. He asked too late unfortunately but that was a part of the reason snake got into brawl. since brawl's release, there have been few new Metal Gear games [not that it matters since i think recency doesn't apply to third party] but no original metal gear games on any nintendo consoles... since the NES? Snake Eater was a port. I personally picked Simon Belmont because he's castlevania is significant enough to nintendo's history and they regularly release new games from that franchise on nintendo consoles GBA, DS, 3DS SNES, N64, Wii. Also there was a new Castlevania that came out earlier this year. And to me, he seems one of the best candidates for a moveset.
Bomberman I personally see as too limited [if anyone is going to flame me on this one, just send it in a PM please]
Snake I don't see as being a true representation of himself. I wasn't bugged about it much, i simply found it silly how he was essentially Demoman [see above]
Simon could bring both the diversity without the blood and gore, y'know cuz he wasn't killing people. just ghouls.