Real Madrid have Eder Militao and David Alaba as centre-backs now and they are the starting eleven players actually. But Ancelotti didn't prefer Alaba in the starting eleven yet. Nacho Fernandez filled his place. And they would really make use of a top centre-back actually. Because it seems like they don't seem to be having problems on scoring. But they are conceding goals very easily.
Real Madrid have to focus on their defense system because new players, new team mates will not be able to play smoothly with each other, worse than players who play together in many years.The average age of Real Madrid squad is high and it can be their problems in second part of the season, after the Winter, or when the Champions League goes to quarter or semi final. If Real Madrid can go far in Champions League, they can have troubles with the old squad.
I agree with you on the age problem. I have just checked their squad again and I have seen that their average age is really high. There are not many players whose age is below 25 right now. They are like the new Juventus with old players.
They can revolutionize the team and create a new team with young and talented players. But it is not a thing that will happen in a short time of course. We need time for that even if they think of doing this also.