1. Activision might be more open to the idea of Crash appearing in a crossover-fighter after N. Sane Trilogy and Crash 4 being so well-received.
2. As we've seen, Sakurai can be very persuasive when negotiating the rights for characters. For God's sake, he landed a character from A RIVAL CONSOLE DEVELOPER. After that, I'd say anything's possible.

Smash speculators are an uninspired bunch circlejerking the same 5-6 third party characters because they'd bring the hype™