Voted for Super Mario Switch. It's easily the Switch game I'm most excited for at the moment.
I have a theory about the game as well.
So you know how the only two segments we saw were part of the same continuous desert-like level, considering the beacon of light present in both? And you notice how there's ice pillars everywhere, despite them being incredibly out of place in this level? My theory is that in response to the common complaint that you always go through the same world types (snow, desert, grassland, mountain, water, Sky, lava, repeat), Nintendo made this game which features the different world being combined due to some universe-altering magic or something, and Mario needs to set things right. So we could see sand + ice, Sky + Ocean, grassland + lava, and who knows what else. It could definitely be creative. And it'd fit with the system name. All the world's got switched around.
That's my theory anyway, based on the literally five seconds of footage we've seen.