What I am worried is how will they go for the next generation whenever it comes. Like we assume Ash defeats Leon when the current series ends, then what after that?
Scenario 1: New champion is stronger than Leon- Ash would definitely want to challenge the new champion. But it wouldn't make much sense for him to battle 100 trainers again as he would already be a champion. So I can't imagine how they will make a series of 150 episodes for that
Scenario 2: Ash isn't able to defeat Leon by the end of the current series- But since we can assume that he will definitely have an official battle with Leon by the end of the series, Ash would be in Top8. Then from being in Top 8 to becoming champion will also not take 150 episodes.
Scenario 3: Ash defeats Leon by the end of the series and in the new series, they revert to old formula of travelling the new region collecting gym badges- Wouldn't make any sense after Ash defeats the champion.
Scenario 4: Ash remains a Champion and continues his journey as one, by accepting challenges from other challengers to the throne- Seems like a possible one, but in this case, Go/ any new co-protagonist would have an increased role to fill the show.
Scenario 5: they either reboot the anime/ or introduce new main character, and Ash is just some recurring character- possible, but this Ash and Pikachu are anime Mascot, I find it hard to believe they would leave the show if the show is still running
Scenario 6: Show Ends. The End