Like others have said, I wouldn't expect any 3rd party online-only/primary game to even be announced until Nintendo's whole "online service" is out. None of us even know what it entails and, the way things have been so under wraps with the beginning of the Switch launch, I doubt devs know anything about it either.
Well, I guess there is Xenoverse 2, but we don't really have any deets on that...
I'm cautiously optimistic though. Haven't played the game in months, but if I could pick up and play randomly throughout the day, this game would live in my rotation permanently. Impromptu Splatoon, Mario Kart and Rocket League matches would be the death of me. I rolled over in bed Sunday morning, grabbed my Switch, and was in a Testfire game within 2 minutes. Felt almost magical for a moment.