I've been a little tardy with this thread recently, so I apologize for that.
It does seem that, beyond some miracle, things are most likely curtains for Lycanroc in Smash. That being said, I wouldn't say Lycanroc didn't leave a legacy. He still stands as a defining icon of Alola, the second most popular rock-type after Tyranitar, Ash's main Pokemon for the region, and the one who finally broke the Pokemon League curse. That last one in particular is pretty big, as it makes me think that Lycanroc will may get a second wind a decade from now, when kids who grew up watching the Alola anime and Lycanroc become major parts of the Pokemon community, similar to how Sceptile got a second wind about a decade after RSE.
Even then, that's also not to say we didn't leave some sort of legacy behind. We fostered a community that I am more than proud to be part of and I have enjoyed immensely. The fact we were able to outlast and outgrow basically every other Gen 7 Pokemon on this board definitely means something. Even Incineroar, the Pokemon who actually got in, had his social thread go the way of the Dodo a few months after release. In terms of a more tangential result, the fact that Lycanroc was one of the first Pokemon announced to be returning with the Isle of Armour means Game Freak has to be somewhat aware of his popularity.
Ultimate's relationship with Alola is a little... underwhelming. In Smash, Alola has 10 Pokeball Pokemon, 6 tracks (some of which are considered the some of the weaker ones and inferior to their original counterparts), and about 14 spirits (not counting Partner Pikachu and Eevee), that's not a ton of content for a major new Nintendo release. Likewise, we have Incineroar, a character who doesn't really reference his source material that in depth and has a questionable longevity for future Smash games. It's kinda clear that Sakurai didn't really click with Alola that closely and chose to prioritize other stuff, but that's alright. Ultimate is still an amazing game I wouldn't trade for anything. There's more a region's worth than it's representation in Smash. Plus, Alola is still doing better Unova and Hoenn. How Alola will be represented in future Smash games is kinda up in the air, but that's a problem for tomorrow.