Real Madrid is a team with a very large player pool. Kroos' departure will not have a shaking effect on the team. I'm sure Ancelotti has many alternatives in mind instead of Kroos. Kroos moved away from football at a somewhat early age. I think he could have played top-level football for 2 more years. Still, it's his choice and we should respect it. Real Madrid needs a quality midfielder for now. Let's see who will do this next year.
Toni Kroos departure will not have much of an impact on Real Madrid performance, Ancelotti still has other players who can replace his role in midfield. It is not too difficult for a team like Real Madrid to find a suitable replacement to replace Kroos, especially now that they have Bellingham who has excellent goal scoring abilities.
Kroos decision was very surprising because he is still able to play at a high level and his abilities are still very stable, but he chose to rest sooner than expected. Real Madrid must prepare an ideal replacement because soon they will be left behind by Modric.