I too, would love to see another F-Zero and Star Fox. Out of the two, I feel F-Zero would be the easier one to pull off. Give me one with a more heavy metal soundtrack a la' X and I'd be a happy camper right there.
Star Fox on the other hand, I feel the series is in a tough spot. They have to escape the 64 remake cycle, yet the fanbase keeps screaming anytime the series is not like 64. I would love to see them go in a bit of a sandbox direction with the Mercenary aspect of picking jobs to do, but there's just no telling what the company itself will do.