I think the WiiU will be a success, but obviously not a Wii-level success.
I think the next gen will be a repeat of this gen where all 3 consoles are ridiculously successful, just the final placement ranking will shift.
Barring some drastic misstep, Microsoft should win Generation 8, and then it'll be a battle for 2nd between Nintendo and Sony depending on a lot of issues that we don't know yet at this time.
--
Thank you, Eddie Guerrero.
http://bryandanielson.net/wp-content/uploads/2011/12/photo3.jpg