Btw last year's Nintendo keynote was very good, I don't get "it's gonna suck" comments here. I don't expect it to be amazing but Nintendo generally has found a good flow for these things.
@BN: They did a Smash direct on Sunday purely so they could keep it from bloating up their E3 keynote. I don't think they even mentioned MK8 at last year's, but more tracks are always welcome.
Star Fox is confirmed, there's a strong chance of Metroid Prime Hunters 2 showing up, and Satoshi Tajiri came to LA so there could be a mainline Pokemon announced (or it could just be confirmation of Pokken coming to home consoles/US.)
Besides that, who knows. Nintendo stuff generally doesn't leak. If Retro is showing something this year I'd be very surprised since their stuff always leaks one day ahead of time.