I think people only expecting a small bump from the Nextbox will be in for a shock, look at NGP for starters the handheld war has not put Sony off sticking to their DNA and going for power. 360 is going to be at least seven if not eight years old by the time Nextbox appears, even for a reasonable price they will be able to put something together that blows 360/PS3/WIIU away with ease.
First of all it's the vita, second of all that proves nothing.
Of course it proves something, the approach of the DS has not changed what Sony did spec wise with their handheld, fact. I don't see why that will not be applied to PS4. Microsoft are not going to be left in a position inferior to PS4.
The rumour is that WiiU has a 4*** series ATi custom GPU, that's already 2 gen old as of today, by the time Nextbox and PS4 appear it will be at least three if not four gens behind.