Firstly, I don't think that the tablets and phones are taking territories away from the consoles.
The Wii/PS3/360 generation and the DS/PSP generations are the most successfull generation so far in the industry.
That being said, I don't think the Wii U will hurt tablets because it is totally different. I highly doubt that the Wii U controller has a competent processor built in, so it will be very limited when far off the console.