Making some changes is always better I think.
Even after paying high salaries to star players like Ramos, Mbappe, Neymar, and Di Maria, PSG still has extra money to pay Messi! This club is too much rich. Where La Liga's renowned club Barcelona and Real Madrid is unable to buy players due to the financial crisis. PSG is adding one-star player after another to their squad.
BTW I don't think Messi will agree to play with Ramos in the same team. The relationship between Ramos and Messi doesn't seem to be pleasant. Hope, Messi will stay in Barcelona.
Messi and Ramos are professional and the relationship during the match is unlikely to affect the relationship after it. The only problem may be the leadership of this or that player. If there are several star players in the team and each of them wants to be a leader, then this will certainly lead to conflicts. In this case, only a strong coach can solve the problem, but alas, Pochettino is unlikely to cope with such a problem.