I think it's going to be similar to the previous generation, but with a bit less sales for everyone. And a whole lot less sales for the Vita.
The Playstation 4 and Xbox 720 are aiming for a very hardcore crowd. The exact same audience that bought their predecessors. When you refuse to expand your audience with fresh blood the only direction you can go is down. The token effort to reach out to casuals with the facebook sharing crap isn't going to work.
The Wii U on the other hand is off to a horrible start, but it's only a matter of time until those world famous Nintendo games get released and the price drops enough to entice the casual market. Nintendo did a fantastic job reviving the 3DS, so I have little doubt they'll do the same with the Wii U.
I'm calling it now. Wii U > PS4 = 720