Napoli manager will do everything possible to make Osimhen remain in the team next year so that they will be able to win some trophies that will make people to rate the team among the best team in the world. Napoli performance in this season made many people to believe that they will maintain this winning attitude till the end of the tournament, because their players are well organized from the beginning of this season till now.
A more realistic task for Napoli is keeping Osimhen in their club a few more months till a season ending. They need Osimhen to maintain good attacking because Osimhen not only scores goals for them but also can attract defenders of opponents and therefore will help Napoli attacking more dangerous.
I think, Napoli coach will still like to bring in more talented players that will remain on bench in case there is an injury to any player there will not be problem at the moment.
They will try but they will have similar problems of other clubs. After a successful season, their star players will be targets of bigger clubs and some of players will want to move to bigger clubs and find chances at higher competitions.
They will also get troubles when try to keep their star players, increasing their salary, buying new players. Mostly they will no be able to keep up their success but burden from salary, transfer budgets become bigger. A few seasons later, clubs like Napoli will get financial problems.