Nintendo isn't going to fast-track the reveal of the NX just for this game. If the developers decide to postpone this game until NX then the game will just sit on the backburner for a couple of years and eventually get cancelled when nobody cares about it anymore.
23FPS may not be too far from playable for a racing simulator game. A game like Project Cars probably won't have big framerate dips like a FPS games would have. If they can get it to 30, I'm sure that the gameplay would be extremely playable.
The developers should just be honest and port the game to the Wii U with some particles and effects turned off, They can focus their efforts on making the controls nice and responsive on the gamepad instead of going for realism. I think an ugly port of Project Cars will do less damage to the reputation of these developers then if they were to betray Wii U owners by not porting this game.







