Resolves YES if the next Smash game to be released uses most of Ultimate’s assets (models, textures, animations, music, etc.).
This might be a sequel/deluxe version of Ultimate or be its own game.
Resolves NO if most assets seem to be new, or if it’s based on another game (e.g. a port of Melee).
Equivalent markets would have resolved NO for Melee & Brawl & Smash 4, YES for Ultimate.
At this point the groundwork is so thoroughly laid that it’s hard to imagine anything other than deluxe versions of Ultimate.
With Sakurai on a retirement track, it seems less likely that either he or a successor will want to shake up the successful formula.
Easiest thing would be to update a few characters’ movesets based on their most recent games, and then put dev time into things like single player cutscenes, challenges, and so on, with minor QOL updates.
Of course, it’s Nintendo, so who knows.