In as much as talks about Mbappe’s injury suggests that it might be a minor injury, I think Real Madrid will feel his absence more than they would expect. Ancelotti will want him to recover fully, I may be wrong and the team may be just as good or even better without him. Real Madrid has Vinícius junior, Jude Bellingham, Rodrygo, Endrick, Ader Güler, these players are more than capable of keeping Real Madrid on the winning track. Mbappe will be surely be missed but I doubt his absence will disrupt real Madrid from winning.
Despite the fact that Mmbappe has not been at his utmost best since joining the club but he has played an important role as well in the performance of the team and his goals will definitely be missed. It’s even a good thing that he is injured at least the injury might give him some space to regain himself psychologically because the chances missed was getting to him and causing him to perform badly.
With Vinicius presence they might not feel his absence much but who would replace him at his position? Maybe they would go back to playing Bellingham as a false 9 just as they did last season.
I am not too worried about Mbappe's absence from the squad, because if you look at Madrid's schedule in La Liga, their next opponents are quite easy to beat so I don't think his absence will affect the overall performance of the team, and as you mentioned there are still quality core players, besides this condition is an opportunity for Endrick and also Arda to get more playing time.
You’re right, for a while all the opponents will be bottom table teams and so there is really nothing much to worry about and I believe the available players should be able to take care of things while he is away. I am not sure if Endrick can be relied on just yet but it is really time for him to get more playing time and try to prove himself to the fans and everyone, Arda Guler get more playing minutes than him and people have seen what he is capable of doing already.