I'm still not too sure how I feel about him.
On one hand, his loan is expensive as is his salary and there is also the fact that he is always bound to come short in the biggest moments.
On another hand, he has been really impressive in Serie A since the Empoli match, which is one of the main reasons we made it back to the CL. He either scored or assisted a goal in every single game he played. (7 goals 4 assists in the last 7 matches). I still believe when he's somewhat fit, the guy is a difference maker in Serie A specifically. And he was able to step up against the 'top' teams in Serie A - goals away Napoli/Roma, home Atalanta, 2 assists home vs. Lazio. His physicality and speed (although not as quick as before) can still make the difference.
I guess my opinion will depend on who his replacement is. If we can get a young player with pace and goal scoring ability who can contribute, I would much prefer that. However, if the replacement for Lukaku is 1 year loan for Scamacca, I'm not all that sure. Scamacca is coming from a pretty terrible season and was injured for months. I know that Lukaku had his injuries as well, but I still think Lukaku gives some guarantees in Serie A. I'm not sure Scamacca gives any of those.
If we could somehow get someone like Openda, that would be great, but seems like a long shot. Another option is Retegui, but again, I don't know much about him or how much he can contribute. Given that we may struggle to get rid of Correa, the worst option would be to get another player who is a question mark and might not be able to contribute.
Despite Lukaku's failings in the Champions League Final, I've been very satisfied with his performances in the last few games (including the cameos in the CL knockouts and the Serie A big matches). We know his limitations in the biggest matches, and to be fair, if he did not have those limitations, he wouldn't be coming to us for a one-year loan.
Whatever decision we make, we need to only loan him for one year at most - with a smaller loan fee and smaller salary.