Ash is always going to be confirmed 10, that has nothing to do with anything. Obviously we're never going to get a timeskip, they're speaking in the far future long after the shows current continuity ends. Even if we never see it, it doesn't matter, it's implied.
Considering people still bring up old things that happened in the anime from the OS, AG or DP on a daily basis even though they happened years/decades ago, people will still talk about Amour/Serena decades after she left the show too. It's also not like people don't go back and rewatch old eps either, so no old character is truly gone even after they leave the show forever.
Considering people still bring up old things that happened in the anime from the OS, AG or DP on a daily basis even though they happened years/decades ago, people will still talk about Amour/Serena decades after she left the show too. It's also not like people don't go back and rewatch old eps either, so no old character is truly gone even after they leave the show forever.