Modric is a great asset for the club, in fact I wouldn't have let Modric leave Madrid , but Madrid's management want to keep their money and they respect that, so given these things the best thing is what happens, and now AC Milan have a great Midfielder who will surely bring good news to their team, there is no doubt about that, for me AC Milan will be in one of the best teams in Italy.
I might also think the same thing about AC Milan's new season. Besides Modric, I am personally quite optimistic about AC Milan because I believe that Massimiliano Allegri will be able to maximize the depth of AC Milan's current squad. As for Modric, I initially thought he would retire at Real Madrid. I had heard that in previous seasons. But it seems the player was unable to renew his contract there while he still wanted to play.
But it's perfectly natural that Real Madrid would eventually release him when his contract expires, as he's already 39 years old. Real Madrid are currently struggling with their squad, which has begun to be revamped and filled with young players. However, AC Milan were fortunate enough to acquire Modric for free in the transfer window. Although Modric is no longer young, I believe his experience and skills on the pitch are still excellent, and he will certainly become a very reliable player. Even though he's 39, I feel he hasn't lost his sharpness. One of the problems might simply be stamina.