Messi left as a free agent, if I'm not mistaken, so did Ramos. they let go of Neymar, because PSG saw an opportunity to profit from Al Hilal. moreover, Neymar is very prone to injury. currently PSG only has Mbappe, there is no choice for PSG to change their philosophy. from mega star projects, now it is dominated by young players. PSG actually doesn't recruit mediocre players, Dembelle is Barcelona's mainstay player. Goncalo Ramos is a young talent, Kolo Muani has talent that can be developed. plus, the current PSG coach is quite accomplished, at least he won the treble winner if I'm not mistaken with Barcelona in his first season. Apart from that, in the second season Enrique won two wins with Barcelona. at least, he was a pretty good coach. the reason is, not all coaches are able to handle a top team filled with many stars. there are egos among the players, there is also competition, but Enrique is able to handle it well, especially in the dressing room.
With PSG, he did the same thing. now, disputes between players can no longer be heard despite the departure of Messi and Neymar. Just look, how Enrique brings PSG better than Galtier without Messi, Neymar, Ramos and several other players. he proved his worth, that he is a worthy coach. in this season, I'm sure that Enrique is fully aware that his team is not strong enough to compete with other top European teams. But at least, he and his squad will always try to work as hard as possible. In the next season, if Enriue is still trusted as PSG coach, maybe he will be given full support to bring in the players he wants. Apart from that, Enrique's current task is to build his team so that it becomes more established and brings out the talent and potential of its players. that means, he is building the team's mentality to achieve what both the coach and the club want.
Well you're right, Messi and Sergio Ramos really needed to leave the team, it needed immediate structuring that's why had to let go of the Super stars Messi and the rest, sell off Neymar for a worthy offer to the Saudi side, to fund new young talented recruits, well though they didn't start up quite well, but they're doing pretty good currently and with the right coach like Enrique who's achieve quite a lot and with experience, I think their new project would he quite successful sooner or later.
Well judging from Enrique's past experience, it was quick sure that doing very good in their domestic league was assured, even though, Nice tried to pull a stunt at the beginning of the season by shaking PSG a bit, they've still humbled and PSG is at their rightful position. Enrique have tried in capturing their domestic league but now he has to work on helping them doing better in the UCL even though it means them reaching the Semi's, it would really boost them to do better, next season with or without the presence of Mbappé.