Real Madrid can still rely on Luca Modric in one season and about prospective players who will replace their positions have begun to Federico Valverde and Eduardo Camavinga. They have begun to show quality to Ancelotti every time given the opportunity to play.
So is Ancelotti at this point considering both to be used at Real Madrid or one of them? considering they both have shown their quality every time they are given the opportunity to play like you said, Because Real Madrid will not be bad when they have to rely on Luca Modric for another season, because there are many other players who can make Real Madrid strong for next season.
Now madrid already have several young midfielders who will be relied on by ancelotti next season, camavinga, valverde and ceballos seem to be getting stiff competition to replace modric and kross next season, the competition is now more interesting because madrid have also got Tchouameni from monaco, but i think between kroos and modric, ancelotti seems to be choosing one of them to keep guarding the madrid midfield because the experience they have will really help the team, I think maybe ancelotti will make camavinga or tchouameni a new tandem for kross and modric in midfield and I believe the two senior players will still fill the madrid line-up next season.