Removing Osimhen and then replacing him with Lukaku will not necessarily have a positive impact on Napoli. Lukaku is no longer ideal but many people still expect his best performance. In the national team at the Euros how many opportunities failed to be converted into goals and there were 3 goals disallowed by the referee until he finally collected O goals at this year's Euros. As for Serie, it is the only league that still gives Lukaku the opportunity to score more goals, and in the EPL it seems too difficult to achieve.
Osimhen best option is of course to leave and let Napoli reorganize their squad with Antonio Conte. Unfortunately, Osimhen was hampered by high demands by Napoli who wanted to profit from the sale of players whose abilities had declined.
Well, I think and I strongly believe that switching both strikers to either teams would do both teams more good than harm, I mean Conte really wants Lukaku, he's worked with him at Inter and even helped him revive his career, then he was able to bag goals and even win the title and I strongly beleve their partnership once again would take Napoli back to a better level even though they don't win the trophy like they did at Inter. Also, Chelsea needs a solid 9 a Drogba like striker and Osimhen is the perfect player for that role, since he's not likely to be used by Conte and since Lukaku is having same fate at Chelsea, I feel a switch by both players is a win win for both teams, Napoli's demand for Osimhen might seem very high but Chelsea could include Lukaku plus a fee for Osimhen since Conte is really interested in the reunion with Romelu Lukaku.