So a Wii U game is peak performance for Switch? And because of that, 3rd parties will abandon the console? And because of that, people will stop buying a Switch?
Of course it's shown its peak performance with a wii U game with a lot of frame rate dips even with patch 1.11. So really don't expect to see any leaps in performance to 1080p/60fps or even 1080p at constant 30 fps in any of the next major installments. Games are now stepping up into 4k resolution and 1080p/60fps on the other consoles. So yeah you're likely to see Switch library diminishing to 1st part games only exactly like what happened to the Wii U simply because it has way too little to offer , in terms of performance, to developers compared to other consoles in the market.
If it struggles with a game like the one shown below with dumped down graphics then really don't expect much from the switch, performance wise, in the following years.
The Switch is still in its first year and this is where most of the consoles are sold to the Nintendo die hard fan base so it is difficult to say it's a success from now. The next 2 - 3 year is where we're going to know if it is a success or otherwise. The easy thing to predict is that without a good 3rd party support for the console , which I suspect that it's going to be the case with the Switch, then it will likely end up being a handheld Wii U.