To me it's been funny. The Switch has been one of the best Nintendo consoles in regards to third party, thanks to the huge number of smaller and indie developed games it has gotten. The Switch has a few first party highlights, but most of their big games have come from Wii U.
I have only bought those I skipped like Hyrule Warriors which combined the content of both Wii U and 3DS.
I think this generation Nintendo's focus has been on branching out. Their mobile initiative, their amusement park, their toys, collectibles and merchandizing their IP. Odd projects like Labo, Ring Fit Adventure, etc.
New big games with high budgets are few and far between.
In regards to the Wii U, as of now, I've still used it for stuff the Switch hasn't gotten yet. Wii, GBA, N64, DS, and unofficially Gamecube games.
If anything that's the stuff Wii U still retains.
And Star Fox Zero, because we likely will not get a new Star Fox on the foreseeable future.