I don't think, Napoli will be able to win this Italian league title next season because one of their potential striker is willing to join premier league team next season to showcase more skills in a way he will have a good record from the team like the way he got a good record from Napoli by helping the team to lifted Italian league title this season. I believe, Napoli management will do something fast that will make the team stronger even though they will not achieve next season title, they can take second or third position from the tournament. Next season will going to be a tough season for Napoli, because it will be difficult for the manager to get a young talented striker like victor Osimhen in this summer.
There is always a plan B underneath every move a team makes to cover up if plan A fails in the long term. That is why they are substitutions in football. Since Napoli has recently been connected to other teams who are interested in him, the scouting department would be preparing for that, or perhaps a replacement is already in place. Victor Osimhen's departure will be a significant loss for Napoli in terms of striking and finishing the game on the first touch. Whatever Osimhen's decision is, it’s fine with me because he has done well to catch the attention of several big clubs.