Pokémon Anime Pokémon Scarlet and Violet, the next anime series after Journeys?

Yes, the anime is going to continue. As long as they still make money off of it, the Pokémon anime will never end. As for whether it will be an adaptation of Scarlet and Violet, I can't say. They may want to go back to the standard formula of loosely adapting the games or they may do something else like with Journeys. It's a bit too early to tell right now but I'm sure we'll get some info this Fall.
As for Ash's involvement, I don't know. I don't think they'll write him off the show (Pikachu definitely isn't going anywhere considering its role as the series' mascot) but his role may end up changing. They've taken the character to new places lately by making him one of the world's top trainers and all that, which would make it hard to continue his story as it has been. They may reset his character development like they did for Best Wishes and have him suddenly be treated like a novice again but that would be strange after building him up so much these past few years. My theory, more of a hope really, is that they're going to have Ash grow and mature into a mentor for a new trainer, with the next series being about him training this new trainer as they go through whatever challenge Scarlet and Violet brings (we've seen some stadiums in the latest trailer but they haven't been confirmed to be gyms yet).