The biggest appeal of the Mario Kart series is local competitive play, that much is clear. 

Since Mario Kart 64 is always been four people on the couch. The rest had to watch or take turns.

Not any more. Sonic Racing Transformed on Wii U already broke the four player barrier by offering a 5th screen via the Gamepad, and as the Wii U is said to support 2 Pads eventually, the logical next step would be to launch this feature with 6-player local Mario Kart;  4 on the TV, two more on each Pad.

Please Nintendo, do yourself a favour, and make this happen.

would be awesome, also they could up the racers from 12 to 16 and added clan wars to the game. not sure if im more hyped for this or gt6

that would be awesome

Does the WiiU support 6controlers at once? I know for a fact they can do 5 (4controlers+1gamepad), I also know for a fact that it can theoricaly handle 2gamepads. But the question is, can a 2nd gamepad be added w/o the cost of ditching a other controler?

But I agree, 6players in a living room playing MK at once would be awsommme. But I seriously doubt theye will. Nintendo never seemed too interested in dual gamepad in the first place and only added the feature because of the high deman. And still they SAID that they added the feature a while back, we still have no proof of that (altho I doubt they would lie on such a aspect). I seriously doubt we will see anything using dual gamepad at this year's E3, I'd go as far as to say that I would'nt be surprised if ever.

they'll have to cut the framerate on the gamepads then.

2012 E3 Nintendo said that WiiU will have dual gamepad support. I believe specifically they said "next year" which would be 2013. So, depending on the games they were thinking of, we'll hopefully see something at E3.

That would be awesome...

No I'm happy with 4 player splitscreen, if they want to add a 5th player on the gamepad I'm ok, but I don't want framerate drops ala MKWii. Follow the MK7 path and make it as much traditional as possible, fine-tune weapons, make it balanced, polish controls, add content; don't waste time on gimmicks.

I think 5 players is good enough.

I'd rather have a solid 30 fps + good graphical detail than 6 players.

Mario Kart Wii chugged too much in split-screen.

5, yes.