Yup, I think he's asking about any potential MOBA crossovers which may include skins or heroes / playable characters, like Amaterasu in Dota 2 (who's a courier, not fully playable though):
Or the "Dante in LoL" rumor. It's one of those things where the announcement will come suddenly, such as
a number of DC Comics characters* in a mobile MOBA (yes, Arena of Valor).
*Those being Superman, Batman, Wonder Woman, Flash and the Joker. And yes, that game saw a Switch release... only to close shop a year later. The mobile game's still performing pretty well in SEA, to the point where
it was featured in the SEA Games likely as a test run for e-sports' potential of becoming an Olympic discipline in the future. And I've suspected in the past that AoV closing its Switch version helped lead to Pokemon Unite being a thing.
Nope. Not what I know of. But if there are any upcoming ones, the announcement will probably be made suddenly as said.
If I may ask, are you talking about the Smash community as a whole (I'm getting that impression) or specific segments of it? I just want to be sure since I got a little confused.