Indeed, in terms of adaptation Lukaku must be very familiar with INter Milan. But now his productivity has dropped dramatically after they sold to Chelsea and returned on loan. I know what you think, maybe you think that in the next season he can play much better than last season and I also actually agree with that. But maybe Inter Milan see other potential coming from other players besides Lukaku. And the problem is also that Chelsea is also like hanging Lukaku's status, they don't expect Lukaku to be in the squad, but at the same time they don't want to release Lukaku permanently.
Yes that's the reason why Chelsea loaned him back to Inter Milan last season, he couldn't make the contribution expected at Chelsea. The reasons for productivity and decreased performance made Chelsea not want to take the risk of losing too much, high prices were not a benchmark for the productivity of its goals. Inter did not want to spend more than 35 million to buy him, because Lukaku demanded to become the main striker for Inter coach Filippo Inzaghi. In fact, if Chelsea want to let Lukaku go below that number, it is possible that many clubs will want to sign him.
It is most likely that Lukaku will move to Juventus after being hanged by Chelsea for so long, and could possibly go to another club depending on the negotiations going well. My prediction is that Lukaku will still be able to contribute next season to the club that recruited him because looking at his statistics in his second season, Lukaku always looks impressive except when he was with Chelsea.
In the end Lukaku was one of the players who made Chelsea lose 2 times in terms of transfers so they also didn't want to let him go that quickly which made them take the option of a loan to get his form back but this did not go well.
Lukaku and Juventus are still linked now and this is what makes Inter look for other alternatives (now Morata) to be their next target.
The problem in this case is that if Lukaku decides to go to a rival this will obviously spark new drama for Inter and Juventus and I expect this to happen because with transfers like this it will increase the intensity and tension in the end.