Poppy JR.
Smash Apprentice
I think it would just be wrong to not include gamepad support. Gamecube controller support would just be icing on the cake.I'll agree with you on sales, lack of dev interest and competition, but I really don't see what the controller has to do with it. F-Zero would play just fine with the Game Pad. Yeah, it would be clunky and it wouldn't be optimal, but that's where the option to use things like the WIi U pro controller and the classic controller come in.
And I don't think online would be too much of an issue either. It's entirely possible to get a solid netcode for it, if Nintendo cared if enough.
I agree with you about online. I mean, look at Mario Kart 8! Smooth as butter online, even on fairly slow connections. I don't see why it would be any different for F-Zero, unless your connection is absolutely abysmal or something.