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The Pokemon Anime was clearly meant to go rotational with their protagonists and tone after DP. This was backed up by the fact of the narrative of DP not foreshadowing Gen 5 or even featuring any teaser except for the Zoroark in the 13th movie. Additionally backed up by the fact that Ash's character portrayal underwent too many drastic changes to either stay on a consistent progression or to just fill the need of the current series, BW being the testing ground which showcased that Ash might as well be replaced and it would've been a improvement, XY (Not a hate post to Mr.L btw) which went over the top and was a misplacement chronically, SM and JN being ridiculously over the top with his character portrayal, inclusion of past events or the consistency one would except from the accumulation of a decade long journey.
Realistically speaking we should've gone this way:
>BW: Hilbert
>XY: Calem
>SM: Elio
>Galar and onward is free game with their protagonists
What TPC is doing now recifying that mistake a decade to end their longest running character on a narratively high note and to honor Team Kato because effectively most of their OG staff members have retired since DP, lost their edge over the years and/or are simply becoming too old.
TL;DR: Ash should've been retired after DP, and this is my opinion as someone who loves DP and XY.