There are a few hiccups, but you can actually play Switch games with GameCube controllers via the USB GameCube Controller adapter. This support came with the 4.0 update to the Switch system software. There are two obvious use cases:
- A new Smash Bros
- GameCube Virtual Console
There's a third possibility too: Nintendo may be opening up the Switch to allow it to work with any USB gaming controller in an effort to give developers more options for porting.
I don't know about you guys, but the GameCube controller still remains one of my favorite game controllers ever made. Plus, I'm excited for a new Smash or GameCube Virtual Console games. Of course, two out of the three Star Fox games with Krystal as a playable character are on GameCube.
Update: Looks like the third option was closest to the mark. Nintendo didn't even know they were enabling GameCube controllers. It was a byproduct of planned future support for third party controllers.