As others have said, you cannot easily replace any major player when he leaves a team. Much more so a unique maverick type player like Eze.
I think we need to be looking at potentially two players (I hope one of them is Esse) who are in the same phase in their career, and who have as much potential as Eze had when he joined us. If El Khannouss is one of those then great that works for me. If we cannot secure someone permanently then a stop gap like a Chelsea loan or Gallagher would also make sense to me provided the sums add up.
I still think we need a back up for Munoz and another CB. I'd see these as more pressing given we have Esse, Kamada is coming back, and Devenny can do a job.