Why Ash probably won't ever step down as the protagonist for the anime (Context: I've been seeing the classic "Will Ash leave?" videos crop up again)

Yep. Like people are obsessed with the idea that the show must end if Ash becomes #1 in the world even though that just opens up hundreds of episodes of Ash being #1 in the world. Ash goes to Paldea, ends up having a mock battle with champion whose normally weak to Electric Pokemon Terastallizes into a ground type completely countering Pikachu to teach Ash that he still has a lot to learn. He'll even be like 'It's like Leon's Cinderace but different neat'.

So Ash makes a new friend, new friend does the badge run of the region. Ash trains new team with local gimmick in mind. Rocket shenanigans. Dealing with local villains. Ash wins some battles against top trainers of region. New kid learns Ash is #1 in the world. New kid now aspires to topple both region and catch Ash. Cameos of Ash's old friends.

Hundreds of episodes right there.

/r/pokemon Thread