I'll say one thing about the power issue - it matters less each time.
The Wii was inferior to the PS3 and 360 and you noticed every time you turned on the machine. It was SD and the others were HD, and as a Nintendo fan it hurt. You wanted to be playing Mario Galaxy and Metroid Prime 3 in HD, and after extended play sessions on those two it was always weird going back.
The Wii U was so stuck so far in the past that it wasn't much better from consoles released 7 years before it. It was almost ludicrously late / underpowered for the year it released. But because it was HD, and because Nintendo's franchises tend not to be realistic, that gap didn't feel like it mattered nearly as much, if at all. Where it did count, obviously, was with third parties. That hurt them.
Now that we're into ever-diminishing graphical returns, I really feel like anything even approaching the PS4 would be acceptable, and anything beyond it will be... well, frankly not that noticeable, and perhaps negligible. At this stage all that matters is how easy it is for third parties to port their games, which is just as much about SDKs, documentation, co-operation etc as it is beating the opponent's specs.