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.
It's part of a regeneration process, Luca Modric can still be relied on but still has to be with his portion, or in other words give their young players the opportunity to play more. I'm sure these midfield generals will pass down the passion to their generation. Ancelotti's intelligence will be decisive in seeing the situation, when to field young players, when to play senior players, and also when they can play together.