I can see that, but Ash has been used enough already and self-reboots have pretty much ruined him by this point. From my point of view, I honestly don't care anymore if Ash is the main character in the anime franchise - just bring in someone new as the protagonist, do what the movies did and slam the hard reboot button, or just end the anime. There's people out there (and I mean this, it's not an April Fools prank) that HATE the self-reboot treatment Ash has been through.
Jaden Yuki grew up, the Digimon protagonists grew up, and even Raiden from Metal Gear Solid 2 grew up. It's finally time for Ash to do the same... FOR GOOD.