WiiU Pro controllers should be supported. I see no good reason why not.Except to sell more controllers...
No Gyro, no HD rumble.
I love the controller and I use it for Wii U and PC local MP gaming relatively often, but it's time has come and gone.
Edit: They present the Pro Controller to be fully functional in games like Splatoon 2 e.g. - having a different Pro Controller with a different layout that doesn't have full compability would only confuse everyone.