There's no way Real Madrid would just let him go if his role wasn't that important and even though he knows he won't be able to strengthen Real Madrid forever, at least his services are still needed before the regeneration of Los Blancos' young players can become more mature. Maybe if you have seen the comments of his former Real Madrid teammate, Isco, he once commented on Toni Kroos' post and asked him to play in the next 2 or 3 years and Toni Kroos actually got a lot of support in this regard.
Yes, even though Madrid has many young players who are ready to replace his position, it doesn't mean that Madrid will easily let him go, because Madrid's main squad requires people who have experience playing there and Kross is the right person to play in Madrid's main squad, that's what is possible. ensure that Kross will stay there, especially as Madrid has made a big name, so it's impossible for him to return to Munich, unless that's his decision.
I also believe that Madrid needs experienced players to manage the game on the field so that they always show their best game and get good results, for example winning a match, especially this UCL match, of course he also wants to bring Madrid back to win the UCL this season where their journey has been thwarted. by Manchester City last season, of course Madrid still needs him in the main squad and he is also not old enough to still play in Madrid where he might be able to get the comfort that he doesn't get if he plays in Munich. but whatever it is, the decision remains Kross.