Star Fox 64 3D sold reasonably well, for being a basically-dead series. I think it's very likely that or F Zero could be getting a Wii U installment sooner rather than later. But I wouldn't think Retro would be working on either of those. I bet Retro is doing something Metroid-related.
A dream come true would be cooperatively developing Wii U Zelda with EAD and doing a 3 year development cycle in half the time. Now THAT would just be absolutely amazing.