WiiU has no good games, i personally dont like Nintendo games anyway. But it sells on Metroid, Mario and Zelda and those games are never launch titles. Plus, apart from those main titles, there are many games not being made for it eg Watchdogs. I think they tried a copycat the Wii fame but i guess lightening doesnt strike twice.
PS4 i fear, from what im hearing, may charge to much again and stall. The PS3 sold well when the price went down, but at the start it was to costly. An they have money problems, and did say this is the first time SOny was in profit in 5 years. Except most of that was laying off staff, closing companies and selling property.
Nextbox i think will do well if they show amazing games and the rumours around it are not true. Also it has to be at a good price point, around £300 would be fine. This goes for PS4 as well, £300 and great games shown at E3.
I think launch dates, well apart from PS2, will be slow. I think the hardcore fans will buy it day one. Every one else will still enjoy there PS3/360 games for maybe 6 months to a year and buy next gen then when there is a more built up library of games. If you look at the PS3, really slow start, but once they were realistic with the price of the hardware and the amazing games started to be released/previewed that machine sold loads.