Edymion
There really is a slight problem with that. In the realm of Nintendo, Hyrule and the Mushroom Kingdom are two wholly separate worlds. I think they're going to stick to games like Smash Bros. in order to have those two appear in the same game...
Well let me say it's nice to see that you still know your stuff Edymion. But i think it could work if they go the Kingdom Hearts route and make it so that the main character has to add nintendo Hero's to his team while traveling from world to world...(even if fhe doen't keep them there, which is what happends in Kingdomhearts)