Dembele is not a very bad player but I don't think he'll last at PSG because of the injury crisis he's faced over years when he was at Barcelona, he's become an injury prone player and that's what I expected Luis Enrique to be worried about before bringing him into the team, tge €50m they spent in getting him would had helped in attracting players like Kudus that's currently at Westham or other youngsters out there doing great.
PSG would had learnt from their experience with Neymar but they sold him to get another player that injury prone as well, however they got other interesting talents that would help them in future the team finally recocer their form, however if Enrique wants to perform well this season he'll need Mbappe's help and play him on his rightful position.
but still Dembele will not be able to perform as optimally as before he was injured and this time at PSG he has indeed made a very good contribution but all that will end after seeing PSG mainstay striker leave this team because Dembele will only be a player who provides feedback to Mbappe needs to be able to provide scores and if Mbappe leaves like Dembele he will also have difficulty working with players who have more reliable talent. I also remember the Neymar case but somehow PSG did not learn enough from that problem and I agree that there is a possibility that Dembele will not last long at PSG.
the difficulty that Enrique is currently feeling is only about players who can replace Mbappe because it seems quite strong that Mbappe will soon leave PSG and if he fails to bring title to this team, I dont think Enrique will last long at PSG either.