I think Toni Kroos will play another 2/1 season in a Madrid jersey. Kross is only 33 years old. And Kross's fitness is good enough. So at least two more seasons we will see Kross with Madrid.
Luka Modric is now 38 years old. He is also one of Madrid's most important players. While Modric may stay with Madrid this season, it is very likely that Modric will not be with Madrid next season. Ancelotti brought Bellingham into the squad as Modrich's replacement. Bellingham has adapted to Madrid's gameplay very well. So I would say that Madrid has been able to produce a worthy replacement for Modrich. Now the Madrid management has to find a suitable replacement for Toni Kross.
Compare the ages of Modric and Cross, and you can imagine how many more seasons Cross can play in Real Madrid if he wants. Last season, Real Madrid did not have Bellingham, and in the new transfer window, Real Madrid can sign a contract with another talented player, this is not a problem when the club has money. Modric is technically a very talented player, this is what allows him to play at such a high level despite his age, but he will not be able to play at this level for a long time.
If he wants to continue his playing career, he will probably have such an opportunity in other championships, but I think that he will simply end his career and rest for a while. I suspect he doesn't want to go to Saudi Arabia for the money.