Neymar leaving PSG for another club is a possibility because teams and fans have stopped talking about him and are now focused on how to enhance their squad. That sum is too large for any anyone not to accept and join them. During his time at PSG and Barcelona, Neymar has made significant contributions. I believe he should join the Saudi team, where he will be better respected, even though his worth as a player is limited at his current level.
Since Messi has moved on to another club, I reckon Neymar would follow suit even if it means he has to force the transfer by himself. Messi coming to PSG was one of the reasons why he stayed for a few more seasons. PSG fans do not deserve him and has always disrespected Neymar even at times when he made the most contributions to the team.
I think this should be decided soon, as Neymar's relations with PSG are in turmoil and his continuity in Paris seems increasingly uncertain.
Yes, he should leave whenever he gets the chance. It's super difficult to strive in negative-impact environment. With Mbappe move imminent staying back will only cause more damage to his career.