Modric is still there to do what Kroos does but it won't be effective because the physical strength is no longer there and he would not be given as much playing time. Valverde will be the centre of attention, let's see what his performance will be.
Modric will still do his role as he did before and I don't think anyone can replace the role of Kroos at the moment because after all Kroos has his own role and not all players can do the same thing as Kroos especially with the passing accuracy he always has which is always above 90 percent. That can't be replaced by anyone else at the moment in Madrid.
But with Modric there, Madrid will be more comfortable because even though Madrid lost their sniper, Modric can still make a slightly different contribution because he is still one of the best playmakers. In addition with him in the squad at least with the experience he has, of course this will be more beneficial for Madrid because indeed the young players can learn more in terms of mentality and consistency to Modric next season.