I don't think Napoli are ready to lose their keyman to any elite club this summer, they've solid plans for the Nigeria international and keeping him would be their absolute decision.
I don't agree with what you say, because reportedly Osimhen is not included in Conte plans and even Conte has previously said that he wants to see Lukaku in the Napoli squad next season, from what is happening now we can conclude that next season if Osimhen still in the Napoli squad, it is none other than because Napoli failed to sell him at the moment, in the last few weeks and even Fabrizio Romano has confirmed that Napoli is currently in negotiations with PSG regarding the possibility of selling Osimhen at this time, so I think that Napoli never had the intention to retain Osimhen next season if there is a team that can meet Napoli current price request.
You may be right because we have not really heard anything in regards to that case about the Nigerian player in Napoli, perhaps it could be that Napoli has realized that the player still have a lot of things to offer them if they decide to keep him, well considering the condition of the transfer market were every club is currently trying every means possible to make there club strong no club will like to sell there player that's still very active on there front line, so I agree with you because with the look of things I don't think he will be leaving Napoli this season maybe if they are to sell him it will be after this upcoming season because the competition is too much on this season.
Osimhen has actually received a lot of interest from PSG and also English league teams, but the high asking price from Napoli is an obstacle for Osimhen to leave at this time, PSG and Napoli have had several talks, but so far they have not received a final decision regarding the price of Osimhen and according to fabrizio romano latest tweet currently PSG have also withdrawn from their interest in osimhen.
Source : https://twitter.com/FabrizioRomano/status/1815653575202165012?t=wq4Cu8xCRJuJ4lLoouKGqg&s=19
https://twitter.com/FabrizioRomano/status/1815431390969594309?t=oxmHhWYC7VNaiO0yPVb8VQ&s=19