I doubt if osimhen has actually lost his form because he's actually been really stressed this season and it's very normal for a player to have a slight decline after been through such rigorous performance ranging from the Italian league games till when he went for the AFCON and than came back to still play for his team and aswell play in the champions league too, he's actually participated in a whole lot of league games this season so it's enough to get him appearing like a decline.

If he gets to join a team where he's given the enabling environment he will do much more better because at some point Napoli was even affecting his performance in the way he was regarded and treated aswell and i think all those contributed to causing a decline in his performance because they have affected his psychology and given him reason not to be really involved in the team, nevertheless he's performance in most games has still shown his passion and willingness to be a better quality player that just a normal and regular players as he gives his best and all in every of their recent games.

Moving to Chelsea wouldn't be a very bad idea but then there's actually not formal engagement or announcement in that regards if he's accepted to move there but then there are speculations about his possible movement by the end of the season, before the start of next season he would have been rested enough and i think that will aswell influence his price which will means he will be improved and have a better form so it's still very much possible he will be still sold at over a 100 million.