Just a few miscellaneous thoughts.
As was discussed on RFN last week, history has proven that Nintendo is reluctant to create a new IP if they can instead fold original concepts and ideas into their existing stable of franchises. I don't see why Nintendo couldn't do that with F Zero. In my opinion, there actually is significant room within the racing genre for originality (particularly for a game as removed from reality as F Zero). Games like Blur, Excitebots and All-Stars Transformed have shown that you can put a really interesting twist on something as established as 'racing' and have it feel fresh.
Also, I can't say with certainty that a F Zero U would be profitable, but I do think that it would serve a useful function on the system. Most of those Nintendo franchises that have already come to Wii U, and those which have yet to see a release, are quite 'gentle' (for lack of a better word). In other words, they're cute and endearing, but they don't have much of an edge to them. Mario, Animal Crossing, Mario Kart, DKC, Smash Bros, etc, they're all adorable, but sometimes it's all a little too much. Just as it's possible to have too much violence or mature content, having too much cuteness can also be off-putting. I think that's partially why I was so disappointed about the DKCR announcement, because Retro are one of the few Nintendo studios who I believe have the capacity to create something with a little more bite.
It is true that Nintendo are releasing X, and it's publishing Bayonetta and Wonderful 101, which will certainly go some way towards addressing that imbalance; but releasing something like F-Zero (or in my wildest dreams Sin & Punishment) would be exciting despite the fact that it's not exactly a new franchise. F Zero certainly isn't a mature game by any means, but it does have a different flavour to it. I don't necessarily want to see a bevy of Wii U games which contain knives through throats and blood splattered everywhere, but I do sometimes become a little exhausted with just how cute everything is on Nintendo platforms. Sometimes you need a palate cleanser and I think a new F-Zero would refreshing.