Rare=not a chance. Microsoft is a selfish *****.
Konami=Snake only. Snake is the only real person worth adding. If anyone under Konami is added, it will be Snake returning. Snake will most likely be leaving however because "guests" come over to your house for the day and leave later. They don't live there. Same for SSB series: Snake is a "guest" character. He is staying in Brawl for the "day" but will not be living in there (smash is the "house").
Sega=See Konami. Sonic is the only viable Sega character, however he might stay due to a..."lacking" moveset (comedians should make his d-special and side-special a joke or something
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) and a last minute appearance in the SSE (Sakurai really jipped him;
at the VERY END!!!)
Namco=I'm not sure about...I pass this one to someone else...
Capcom=MEGAMAN (X?)!!! He will make it to the next Smash
IF Sakurai adds another 3rd party in "Mayhem." He is famous, has MANY series (though a few of the recent ones were sh*t), and is the icon of Capcom. His popularity is HUGE, too (not as big as Sonic's, though...).
Square Enix=though you didn't say this one, but it's noteworthy. Geno (I don't really support him but he's still mentionable regardless) has the popularity. However, since some of the criteria of a smash character is to contribute to Nintendo's history...Geno was in only one game (a good game, I'll add [though I never played it]), and that's not really contributing...is it? Not dissing Geno, just throwing it out there...
The next two big candidates for "Mayhem's" 3rd party options are MegaMan and Geno...
ALSO!!! I have a question...
Would MegaMan be in his traditional NES originating wear w/Mega Man moves, or would he have his X series (SNES) wear w/Mega Man X moves?