The real problem for Real Madrid is their midfield woes. As we saw last year, Kroos' absence significantly impacted Real Madrid. To avoid a similar problem this year, I believe they need to make a transfer in this area. Vinicius, Mbappé, Rodrygo, and Bellingham are all effective attacking players for this team. However, they lack a master of control in midfield. A transfer in that area would raise the team's level. However, they probably haven't figured out who to bring in for this position. I'm sure manager Xabi Alonso has a plan.
Toni Kroos absence made a huge blow to Real Madrid in their midfield control which also exposed the weakness of their defensive line. Players like Kroos aren't easy to replace and I don't think Xabi Alonso can quickly get a perfect replacement to that position except he just gets lucky. And now with Modric departure to AC Milan it all makes real Madrid's situation for a superb performance against Barcelona next season yet uncertain.
I agree with everything that you said. Kroos was the back bone of the midfield and defense, because players will not easily pass through the midfield to the defenders, giving them less work to handle. It's going to be somehow tough for Xabi who still need time to get a good midfielder. Barcelona has always been their rival and let's see how Madrid will manage to play Barcelona this new season without a good midfielder.