Maybe, but what's done is done.I must confess, I NEVER thought they'd rid of him because they kept him around SO long it would be awkward to replace him, or there'd be backlash.
Heck, I thought they kept him around because having the same protag is what gave them a boost over the other Monster Pet series changing the cast every few years.
But here we are. I just hope replacing Ash doesn't make things worse on them and/or they bring him back in an act of desperation...<_<
I would say yes, it is too late to start replacing Ash, at the very least from a marketing perspective. Waiting twenty five years to replace him is far too long and makes the change a bigger risk than it necessarily needs to be given his iconic status. Not to mention if they were interested in giving Ash's story closure, or rather if that was the main objective, I don't think that they would have waited this long to do so. While I don't think having new leads will necessarily lead to the new series being unsuccessful, I also don't think that the anime is going to attract as much attention as it did during the past few series. The accomplishments of any new leads are most likely not going to trend on Twitter like Ash's have.It would be awkward to replace him after Sun & Moon. Even after becoming Pokémon Champion, he was just a Champion of one region that just got a Pokémon League set up (meaning that Ash's challenges are not that big compared to the past). It would be a rushed job to replace him after XY given the prioritization of Team Flare arc as the true finale rather than the Kalos League. It would be an embarrassment to replace Ash after such a poor showing in the Unova League and honestly it would be the absolute worst time (this is when the Red is better than Ash was at an all time high).The best times to replace Ash would have been either with Johto if they wanted to go the Adventures route of replacing the lead with each generation or with AG since that was the first new series. DP arguably could have worked as a send off too. While that still would have been a risk given he had been the protagonist for over a decade by the end of the series, I think that could have worked. Just have him defeat Paul in the Sinnoh League finals and then go off to the Champion League either off-screen or have that be the focus on a set of specials. Plenty of people thought he was going to win in large part because of how huge his rivalry with Paul was and that they introduced the Champion League for the first time. The marketing around Black/White as being kind of fresh starts for the games with no older Pokemon around until the post storyline might have helped with the anime following that kind of transition.
When we get to the classic era, there were problems of ending Ash's story. For one, the final battle against Paul lasted for 3 episodes and Ash was nowhere near the actual Finals, let alone the real dream of defeating Cynthia. It felt like DP was being cut short due to BW, and thus Ash ends his tenure in the League with a technical loss against Tobias and his Legendaries (technically one Legendary and one Mythical). The Battle Frontier was a good place to end Ash's journey with the return of Ash's classic Pokémon ready to give Ash a true victory, but the shadow of the Hoenn League plus the fact that Elite Four trainers and Champions were around the corner always gave that sense that Ash was only a big fish in a tiny pond, which Gary then proved with the last battle. And of course, while the original series did have Ash defeat Gary, Harrison and his new Gen III Pokémon loomed over Ash as the next step/obstacle to overcome at the last moment.
Looking at these the factors, I don't think it was easy to simply replace Ash at any point. There was always that feeling that greater challenges await Ash, and people want to see them. Ash just winning against his rivals or winning a local Pokémon League was never going to be a satisfying end.
When you look at Journeys, there was a critical aspect of that series that ensured a grand finale for Ash: An established world top trainer.
Leon could have been just the undefeated Galar Champion and Ash competes in the Galar League on a local level. But instead, Leon got upgraded as a World Champion capable of defeating other Champions. And when those Champions are the top trainers of their region, even greater than the local Elite Four, suddenly the power hierarchy is clear for Ash. If you defeat Leon, you're the World Champion with no one officially above you. And that fact is what enabled Ash leaving to be a real possiblity. No more guessing if Ash should leave without fighting [Insert Champion] here. Leon is the strongest, undefeated Champion and thus he is the ultimate goal.
Really, could anyone figure out a better ending moment than Pikachu gaining the strength of Ash's entire Pokémon rooster to win the World Championship?
