VGFacts

This might be a hint of her presence in the next Super Smash Bros. or the next Punch Out:

http://www.youtube.com/watch?v=6vLamGGSav8&t=47m27s

Just look at the screen behind her.

Ok, two things.

1: Very broad speculation.
2: There is a thread dedicated to SSB4.
http://www.vgfacts.com/forums/showthread.php?tid=457

But have fun and keep posting!