There are two factors that make Real Madrid immediately look for a replacement for Benzema. First, the age factor, and the second is the injury factor. Benzema's age can affect his appearance, his strength is decreasing, advancing age also makes players more familiar with injuries.
Real Madrid cannot count on Benzema any longer even though he is still capable of making a contribution to the team. To anticipate the worst, Real Madrid must move faster in the January transfer market to bring in a player worthy of being Benzema's successor.
Yes, that's what they have to do, they can't wait until it's true that Benzema can't be played for a very long time. Even though they now have players who could replace Benzema, it is still not enough because we know what they are like when Benzema is not in the squad. After all, now the competition is even tougher in La Liga and the Champions League, so they have to prepare for that.
Well, the reality is that if they could get Endrick, and use Benzema for another 3 years at least, that means for the next 3-3.5 years they would have both Benzema, but also have Endrick playing here and there, like cup games, or league games after important UCL games and so forth. That way, he would improve and become a great player.
Consider how Vinicius was when he firs got here, or how Rodrygo was, dude was very young when he got to Real, and eventually got better and better and better, now he is vital part of it. Same can be done but they have to endure with Benzema for another 3-3.5 seasons, find replacement bench level player like Asensio for example as well, because if Benzema injured, Endrick can't sustain that level now.