Conte's desire to bring in Lukaku could indeed be a wrong option because Lukaku still has the instinct to score goals. But Conte also has to look at the options of several other players whether it would be very suitable if Lukaku were brought to Napoli because Osimhen himself is still not certain about moving from Napoli to another team. Although most people probably believe that Conte can bring Napoli back to compete with the other top teams in Serie A next season.
Before now, it was like osimhen was really certain about leaving Napoli but his desired destination was Chelsea or an English team but since Chelsea opted out of the deal, osimhens fate became uncertain. If Chelsea refuse to let go of lukaku and wants him back in the team, I doubt if he will be going to napoil even if conte desires he play in Napoli. It would have been a very good exchange to have osimhen in Chelsea and lukaku moving to Napoli, osimhen will now have the privilege to having his dream come true.
At Chelsea osimhen will even do better because it has been a place he has desired to move to, he currently don't appear like he's so pleased staying at Napoli for the season, so moving to a new destination especially if it's a place he so desired, will be very much better for him and even his performance may be reawakened because he may want to appear very useful to the team but staying back at Napoli will only be a last option and again he may not give his very best to it
I don't think this will be the right decision because Chelsea is also in a downturn so if he doesn't get strong support from his teammates then Osimhen's performance will not develop and it will also not be good for his career.
I heard several teams want Osimhen, including PSG, so I think rumors of Osimhen's transfer will continue to grow in this transfer market and it is very likely that Osimhen will leave, especially if Napoli manages to get Lukaku.