They still have options if it is needed, but so far Real Madrid hasn't been very lucky with injuries. Losing Thibaut Courtois for so long and then also Vinicius Junior who missed several games at the beginning of the season. But Militao will be out for around 6 months? But this could turn into a problem later on in the season.
Actually only Courtois and Militao who get injured for a long time, Real Madrid already have proper players to replace them. I think Barcelona condition is worse now, they have 7 injured players. Barcelona seems difficult to get proper replacement for the injured players, especially for the attackers. But most Barcelona players don't get injured for a long time, they are only absent for few weeks. Most Barcelona players seem available in the next El Clasico, they are expected to return before the El Clasico match. While Courtois and Militao will be absent, they will retrun on March 2024.
Well, I think Ancelotti already prepared everything for the El Clasico match. Real Madrid has Kepa Arrizabalaga to replace Courtois, he seems quite well. Meanwhile Real Madrid still has Alaba, Rudiger, and Nacho for center backs. There will be no serious problem with the absence of Courtois and Militao. As long as there are no other players to get injured, Real Madrid seems ready for the next El Clasico.
For now they can compensate for these players, but losing one more key player can make a huge difference, especially when the really important Champions League games will start. Vinicius Junior is the best example here as he immediately started scoring again after he returned.
I've explained above, there will be no serious problem since Real Madrid already have proper replacement for the injured players. They will be ready for UCL next matches and El Clasico, too. Vinicius is in a good condition, his fitness no longer has a problem. I also heard the news that Arda Guler will be ready to play as well.