The Nintendo hardcore crowd have been a difficult group to depend on: Sonic Lost World, The Wonderful 101, Sonic & All-Stars Racing Transformed, Rayman Legends, all great games especially for the N-core, has underperformed in sales.

Even worse sales has all good and excellent third-party games had: Batman: Arkham City, Need for Speed: Most Wanted, Resident Evil: Revelations, Deus Ex: Human Revolution (all above 80 metascore).

Not to mention the faboulus games that barley has made their money back: Bayonetta 2, Monster Hunter Tri, LEGO City Undercover (all above 80 metascore).

I like Nintendo games but I am starting to believe that there has to be "Mario" in the title for something to sell well: F-Zero - Mario edition.

About those number games:

F-Zero GP Legends sold bad for a F-Zero. That said, Maximum Velocity didn't and GP was critized back then for being pretty much the same but not as good.

F-Zero X sold pretty good back then for a  N64 game.

So the biggest flop in the series for itself might be GX.

Then there's wipEout:
Pure did pretty good.

The PS2 port of Pulse came very late and compared to other late games did quite well.

HD Fury was the disc version of a download game, released after the download game. So it probably did much better than numbers tell us.

Then there's the unloved wipEout Fusion. That one actually is a flop, but partially because the wipEout fans didn't like it.

2048 didn't sell well. But that is something that happened to most western Vita releases. It's still the 28th best selling Vita game. So overall it may be a flop but it actually did well for Vita standards. And keep in mind that 2048 is still sold with the mega pack bundle and was one of the three basic PS+ titles for the Vita until last summer as well.

I don't see SciFi racers pulling really huge numbers. But i also wouldn't say they have to be instant flops.

Sci-fi racers can probably survive on the indie scene. 

Distance. (Available on Steam Early Access, COMING TO PS4 IN 2015).   http://survivethedistance.com/

Quantum Rush. (Available on Steam). http://quantum-rush.net/?lang=en

Fast Racing Neo of course. http://fast.shinen.com/neo/

If you know about more games coming please let us know.

I voted for DKR!
It looked amazing when it was presented at E3 2001. It would look even more stunning with the graphics of today!

It would have an incredible rooster:    http://en.m.wikipedia.org/wiki/List_of_Donkey_Kong_characters#Diddy_Kong_Racing_characters

http://www.nintendolife.com/news/2014/02/month_of_kong_whatever_happened_to_donkey_kong_racing
https://www.youtube.com/watch?v=0ThbbN3o5yw

Well, there's that butt ugly Wii U title Velocity Stream and The Next Penelope which looks like a top down racing/action mixture.
Then there's Red:Out announced for PS4 and One.
Radial-G will likely also come to PS4.

But the most promising right now is FAST Racing Neo.
FAST Racing on the old Wii looked better than some of those next gen indietitles and the three screenshots Shin'en shared are just awesome.
[img=960x540]http://www.shinen.de/files/FastRacingNeo1.jpg[/img]
[img=960x540]http://www.shinen.com/files/FastRacingNeo2.jpg[/img]
[img=960x540]http://www.shinen.com/files/FastRacingNeo3.jpg[/img]

Shin'en is like five guys, they're really a tiny developer and this is just a Wii U game. And not triple A but an e-shop title.
So i'd love a next gen wipEout that would simply look great as well as a new F-Zero. But Psysgnosis/Studio Liverpool is dead.

I would rather have F-Zero...

I find it hard to believe that Nintendo don't have an f-zero game in the pipeline, considering how much love the series is getting on wii-u with the f-zero track in Mario kart and the minigame in Nintendo land and how loved captain falcon is by Nintendo fans in smash.

I agree with this, even though I don't want to see another Diddy Kong Racing game.  Like it or not, Mario Kart is the most successful game on the Wii U by a wide margin which proves that the install base likes kart racing games.  If DKR introduced enough new concepts to make it different from Mario Kart I can see it selling quite well even though it is another "kart" game.

Like you said, F-Zero would be fan service.  That said, if Nintendo is looking to rush out a new console in 2016 and they want to make sure the hardcorefans are satisfied with the Wii U, it might not be a bad idea for Nintendo to give us a Metroid/F-Zero swan song in 2016 (even if they don't sell well).

DKR would be fanservice as well. All tose Mario Kart buyers would still buy Mario Kart. Just take a look at Tropical Freeze vs. New Super Mario Bros U.

With F-Zero you get another audience, not the same but much less again.

Neither and bring back Top Gear!