Who knows? You must know that age isn't a big problem if the player still can take advantage of the team. Even if Messi will age one year more, I am pretty sure that the interest from other clubs won't disappear. Look at Zlatan Ibrahimović, he was already more than 35 years old but AC Milan still bought him on the previous transfer season (Jan 2, 2020). As long as Messi has no problem with his physical health, then there is always a chance for him to move.
You are talking about talented and strong players. In history of football, there are a few legendary players can play til their fourties at top leagues: Baresi, Maldini, Baggio, Totti, Ibra. There are some goal keepers but I don't want to discuss about them.
Those players are strong (from his youth's performance), and talented so at the end of their careers, they are smart enough to play base their skills that are collected after many years before. Some other players decide to stop because they lost their ambition and happiness when playing football. Or they simply have other priority, families, children, or want to enjoy life without football.
Messi can play well till his fourties if he want but I am not sure he will play well in Premier League after his 35s.