Nintendo doesn't necessarily need their system to be that powerful to make great-looking games, because their games (particularly first-party) usually go with an art style that isn't very demanding.
If devs are looking to make their shader-intensive, "realistic" games then they may have to once again first go to Sony and Microsoft, or preferably the PC. The difference is that this time the Wii 2 will likely be powerful enough that third-party devs don't feel as hamstrung in developing for it.
There's no use in having three different consoles that all offer the same things, and it would be particularly strange to see that out of Nintendo these days. I think they'll stick with a similar philosophy of stylized games that aren't performance-intensive but still look really great. There's room for eye-catching art styles that don't demand significant tech but will look stunning in 1080p, and if performance costs are kept low enough, you could even potentially add 60 FPS on top of it.