I believe that Osimhen is also planning to leave Napoli after the end of his contract. Napoli will be the one at lost, because they didn't get anything from the transfer deal. Osimhen is a superstar and he will definitely get a good club which his impact will be felt. I am happy that Osimhen will finally get his freedom to play in any club of his choice.
At the end of this season, Osimhen still has one year left in his Napoli contract when his loan spell at Galatasaray expires, so Napoli will sell him for a fee. I hear it's around 50-60 million. So Napoli will be making something from the sale.
The problem is, Osimhen has to be relly careful of the clubs he joins next. If he goes to a club that struggles and he struggles, his value might drop and he won't be able to compete with other top strikers in Europe. I think the best club for him before he joined Gala was PSG and I believe its still a good option because they don't have a natural top 9 aside Goncalo Ramos and he's not a starter. They use Dembele as their false 9. If Osimen goes to Paris, he will win titles and he will score a lot of goals because they have good wingers and midfielders.
In a year everything may change, Napoli is unlikely to do anything about the player, they want to get the maximum from his sale, even if the player does not want it, so he will probably play for Galatsaray one more year, until the end of the contract and whether they will sell him to Galatsaray or not - it is unknown, I think Galatsaray itself will want it, but will depend on the desire of the player.