I get the feeling that a fair amount of the Gen 9 lore will get shafted in the next upcoming anime story arc, like how Gen 8 was; little to no involvement of gym leaders, small story plots with the legendaries, and a battle with the regional champion.
I'm okay with the idea of Ash continuing to travel the world, while making stops in newer regions like gen 9. I dont see a point in stagnating him to one region, especially seeing how gen 9 was not had less promotional compared to other previous gen games.
However, I think the new pokemon anime arc will let gen 9 play a pivotal part in the series climax.
As for new pokemon for Ash, I strongly suspect that he will be given a team of legendary and mythical pokemon. I can see the scenario of Ash challengng and capturing rouge legendaries and mythical pokemon. I really dont see a need for him to have a starter pokemon since Ash is now a world champion and is no longer starting out on a new training quest just to compete in a regional league tournament.
Catching legendaries ., meeting Ho-Oh, and working his way to being a true pokemon master is the next big thing.