Luka modric needs to be replaced. he had a good chance but he was not able to do final execution. His shot was not even on target. Barcelona has got less ball possession but it was able to give the same pressure through the use counter attack. The goal that happened with madrid was caused by own goal. Barcelona and madrid played equally in the last match of copa del rey. Benzema tried to make a goal but it was getting annulled due to the off side. Some players like modric get older. It can be seen from his performance in the last match against barcelona was not so good.
Luka Modric is helpful for Real Madrid if they use him appropriately. They can not use Modric like when he was young, because at his 37 age, he is no longer able to play 90 minutes for all matches. In World Cup 2022, he still played well but Croatia had to replace him by younger midfielders in some matches. Modric can be useful if Real Madrid plan to use him only one half of each match and in future, he will more probably stay on bench at match debuts and only join if Real Madric need big changes in attacking.
I hope that real madrid will consider bellingham as a replacement for modric. Real betis gonna be a very hard game for madrid for sure. Betis is now placed in the top 5 under atletico madrid. The draw may become the outcome of the match.
Madrid needs to perform better than when it was against barcelona in previous match. Madrid is always facing hard way to make goal once its opponent used fully defensive strategy.
Bellingham is a box-to-box midfielder and he is not a play maker like Modric. I am not sure that Real Madrid actually need Bellingham as they have Camavinga, Tchouameni and Valverde in midfield. However, it's difficult to find good play maker like Modric in modern football. Such players now barely appear and I have not seen any young player has potential to become new Modric.