As I've said before, I wouldn't and it wouldn't be in line with the NINTENDO spirit.
I know people would settle with GX, HD and 32 players online, but would that really be doing the franchise and its amazing legacy justice?
Have GX function as a starting point from which you flesh out every character and their back story/world more and you've got yourself a priced bovine!
Let some developer get creative with it and add something new to the franchise as well, like space 360 degrees racing when the track launches you into the stratosphere of the planet where you're racing, leading you through thunderclouds and other space anomalies.
I want that world so fleshed out you can literally see the space-hams floating in the sky.