This was expected for some time, but the package Nintendo presented feels half-hearted and incomplete. Super Mario Galaxy 2 and Super Mario 3D World are the obvious omissions, although the latter has also been announced as a standalone release. This raises the obvious question as to why the other titles weren't also released separately. It's possible that may happen sometime next year. The "limited release" that conveniently ends with the fiscal year is a clear tell.
Another big question is whether these titles will be rebuilt from the ground up to take advantage of Switch's hardware power, or if these will be the original games run through an emulator. Given that we're talking about Nintendo, I'd bet on the latter. I'm still slightly miffed that they dumped the Super NES Super Mario All-Stars onto a Wii disc instead of recreating those titles with the NSMB engine, which would have been fan-freaking-tastic.
I really don't want to play Super Mario 64 on a N64 emulator. I'd much rather play it running on the Mario Odyssey engine. Wouldn't you? The weird thing is that NIntendo would clearly make more money if they followed that route. Being arrogant cheapskates only hurts them in the long run. Then again, half the Switch library consists of reissues of older titles, all of which became big hits. So it's not like Nintendo is being cheap for no reason.
If history is any guide, we are now at the point where Nintendo's superstar game designers are becoming bored with their console and want to move on to the next machine. The problem is that console generations are becoming longer and longer, as hardware power reaches a plateau and videogames look perfect in the eyes of most consumers. There's no "next generation" comparable to past eras like Gen-4 and Gen-5. If your company is used to running by a big checklist, that's going to be a problem. Sooner or later, you'll be expected to come up with new songs, and the truth is that you've been coasting on your old hits for years. You've become the band that plays two nights at the state fair, blasting out "Freebird" for the ten-millionth time, and then slacks off at home for the rest of the year.