You've read the title, and you're no doubt thinking, "But how could Ash have a kid? He's literally ten years old." Well, there's one theory that tries to explain that away - a time skip that introduces the new anime's protagonist Riko, going on her own adventure to follow in her father's footsteps after Ash retires from the Pokemon anime to usher in this new generation. And the smoking gun that so many are using as evidence is her hair clip.It's the exact same shape and colour as the logo on Ash's cap, the little green triangle with its right side missing. This has sparked Ash-Serena theories, with many coming to the conclusion that the two grew old together and had a kid. Serena, if you haven't watched the anime, is from the Kalos region, traveling with Ash during his adventures there. In the show, she has a crush on Ash, so naturally fans began shipping the two.Others think it'll be Ash and Misty's kid, given the blue in her hair (rather than her just dying it, which is more likely). Her being Ash's daughter is certainly possible, but we don't have any details about the protagonists yet, and the hair clip evidence could be jumping to conclusions. Alternatively, it might be an homage to Pokemon's most well-known trainer, in and out of universe, or it could be nothing more than the show symbolically passing the torch from one protagonist to the other, with no in-universe meaning at all. The conversation is very reminiscent of specuclation about Rey's parentage from back in The Force Awakens days.
There are even some that think Roy is Leon's, Brock's, or Goh's son, and that he will be traveling with Ash's daughter in what will essentially be a legacy show. The Star Wars comparison is apt, because this would ultimately bring about the same issue it has - shrinking an otherwise huge universe by focusing on one family. Not everyone has to be related. Regardless, that's what many believe from the little info we have to go off so far, and they may well be right.
Some are even calling this the "Shipping War", betting on their favourite Ash pairings. There's the afformentioned Serena and Misty, but even Gen 4's Dawn is being thrown into the mix.
It might be a while before we find out who she really is, if there's any importance to her parentage, but Ash's journey is finally coming to a close on January 23, 2023, with 11 episodes in a special finale limited series.