I've seen a few theories that Ash and Goh might start trying to catch Legendaries, which sounds sort of ridiculous, but I guess you really can't write anything off as ridiculous in this series. Either way, we know Eternatus is coming up, and we also know the Slumbering Weald will probably make an appearance soon too. Tie that in with blue and red colors constantly being used with Ash and Goh respectively, and I think you can figure out where things are headed.
The Alolan crew returning is nice, though I'm not entirely sold on a bunch of other returning characters showing up. There might be a few hints of Brock returning, but there's still a boatload of Galar characters who have yet to debut.
Grookey still being absent is getting a little ridiculous, and I'll be more than a little annoyed if it waited this long only to be caught by Goh and become a recurring Pokemon who "exists".
...Oh, and we're getting Lucario and Cinderace. Anyone legitimately surprised by this? No?