Nintendo need all the help they can get especially when it comes to sports games. NBA 2K believe or not can be a deciding factor to buy a system. The NBA 2k as well as Madden and Fifa fanbase buy that sports game every single year, so that is a big deal to them.

I basically agree for the western developers and market

As much as I hate them as companies, Nintendo does really need Activision-Blizzard, EA, and Take-Two on hand. Those annualized franchises are important from a business perspective as reliable releases to put on the counter and as shelf-stuffers to keep presence at stores high and noticeable. I mean, go to any store and the Wii U section is easily missed partly because it's so small. But a big part of that is because it's missing so many of those annualized releases. Love em or hate em, they serve an important role in keeping awareness of a platform high.

Bethesda is a big win if they are serious, and they usually are. They're a company whose influence has been growing great these last few years and they are a generally well thought of and recognized brand.

But perhaps the biggest win could wind up being middleware producers like Epic. Unreal Engine 4 having no integrated support for Wii U was a major hurdle for projects using it if they wanted to bring it to the U. With UE4 supported on the Switch, that opens the gates to a lot of games that would otherwise be a colossal pain to port.

Cross platform saves would be a good idea to attract third parties.

You don't necessarily have to play the Switch when you get home. You could transfer a save/progress/profile from Switch to PS4/XBO when at home and play Switch on the go.

Nintendo still gets a console sale and a cut of CoD/FIFA/GTA. Who cares what console is used at home?

Depends what you mean by support. We might see games from them on the console but I doubt it's gonna be current AAA ports.

Blizzard, EA, and Ubisoft too, but I agree.