Next season for PSg can be a nightmare if they don't get alternative players for any player they are going to lose, like Messi and Neymar because during this season even with see players they failed to get the results they wanted to get in French League and they failed in champions league however PSG won the French League title but the fact about PSG is they should start seeking for a new coach to gather a stronger team for the next season. However, they will need to invest even more than this season for the next season to rebuild the team.
I think that even taking into account the loss of Messi and the potential loss of Neymar in the squad, Paris Saint-Germain is obliged to take the championship title in France with a margin. And so, yes, you definitely need to strengthen if PSG still wants to win the coveted Champions League. I would not exaggerate so much for the fact of Messi's departure, because strictly speaking, the club simply served as a kind of incubator for Lionel to finally win his coveted World Cup title and also pump up his personal statistics on effective actions in European championships, but globally for what he was called into the team, the goal was not fulfilled and maybe it's even for the best that Messi has gone to the MLS and now PSG can build their game exclusively around Mbappe.
They should definitely still win the title. If you compare the budgets the teams have available and the overall spending on average per year, it would be a shame if PSG does not win the title in the coming seasons.
But there is one more thing that is even more interesting than the overall spending. The fans yelled negatively at Messi and blamed him for not playing well. Ok, then they can't use this as an excuse when he is now gone and they don't win the title.