It's true what you said that the strategy of the coach and players is closely related to the club's success in pursuing targets at the end of the season and Luca Modric was able to adapt to the strategy implemented by the Real Madrid coach since joining in August 2012 until now being coached by Carlo Ancelotti. But with his age now will definitely affect his performance in the future.
In old age, he is still good at providing balance in the Real Madrid midfield, but that will not last long as he returns to his age factor. Real Madrid must immediately find a player who can replace him in a short time. But if you look from time to time Real Madrid never run out of stock of their midfielders. I think they will quickly find a replacement.