Furthermore they’re planning to sell
Casemiro to Manchester United, and I don’t think that they’ll replace him which is another risky transfer from my point of view.
Casemiro's departure will be irreplaceable for now. And his departure is almost confirmed according to the latest update from Fabrizio Romano. It's sad to see Case leaving Madrid. But there's a rumour ongoing that Madrid is considering Bruno Guimares though I don’t think that's going to happen. But I would really love him to see in Madrid. Case will be missing badly in the current season and of course in the UCL.
Real Madrid could always find a replacement for Casemiro. The guy is very old and not much more chance for him in Real Madrid in the next few years. I saw some unconfirmed news about Real Madrid wanting to find a Casemiro replacement, one of the candidates is Tottenham's midfielder, Pierre-Emile Højbjerg. This comes from a tier-2 news runner from England so not very sure but does carry some merit.