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.
Osimhen was one of the best strikers last season so it's only natural that many big teams want to buy him from Napoli. I think the Napoli management will already have another striker if Osimhen does leave in this transfer window. Even though the team wants to keep Osimhen for next season, if there is a tempting enough offer, Napoli management will be ready to release Osimhen to another team. Even Osimhen duel partner on the kvaratskhelia front line is also very much related with a number of big teams in Europe.
So it's not at all surprising that if a team really wants to improve their finances then the option of letting go of a star player would be their solution just like Dortmund did. But still there is a significant setback in their depth of strength for next season. For this reason, Napoli management is expected to decide everything that is best for the progress of the club for next season so that it can compete more strongly at the top of Serie A.