I see some news sources writing like Messi could join Manchester City to look for new adventures if he fails about winning the World Cup. I don't understand the relation between these two events truthfully. Why would Messi like to leave PSG just because of not becoming the champions in the World Cup? PSG are one of the strongest favourites for the Champions League title in the end and they are moving on there now. Even if they don't manage to become the champions I still don't think much thing would change about him.
As long as he doesn't come back to Barcelona somehow, I don't expect him to sign for another team.
These are rumors and many like these are going around because media needs attention from peoples, so they are doing bad tactics like these for some time even few days back he clearly announces right now his main focus is World Cup, and he is not thinking on any other adventure with this he already announces he loves to live in Paris with this we have to understand few things most chances now he is going to stay here in PSG until end of his career because he is doing good, and he can do more good at coming matches with the help of two amazing players Neymar and Mbappé.
About his comeback in Barcelona this is also not going to happen because Xavi also already stated he is happy about Messi who is doing good job for his current club PSG, so we have to wait for next announcement from player instead of going with this shit media.