Lukaku is not in permanent move to Inter Milan so there is every possibility that Chelsea will need him back. Apart from his personal fall out with the Chelsea fans and former Chelsea coach, Lukaku is a fine player that can do very well in England according to his history and I believe Graham Potter will make a very good of him more than his former coach.
Chelsea will not call it a mistake if they want to sign back Lukaku but the only problem is will Lukaku be happy to return to England under Chelsea?
Lukaku has the opportunity to return to Chelsea next season due to his status at Inter on loan without permanent contract agreement at the end of the season. But depending on Chelsea manager Graham Potter's decision whether Lukaku will be included in his scheme of play or not, last season Lukaku faced a very difficult position at Chelsea under Thomas Tuchel, rarely got game time and decided to return to Inter on loan. Seems Inter will find it difficult to permanent Lukaku's status considering the transfer price that must be paid with a fairly large nominal, just have one option for Lukaku return back to England and playing well with Chelsea if want set regular position under Graham Potter.