Carletto loves himself some midfielders true. But he's a pragmatic and that's why he did the Christmas tree formation in Milan because otherwise he wouldn't have been able to fit everybody (and above all Pirlo). Modric may not have been good with Croatia but he was shining with Madrid in this role this season. When Carlo switched to 4/3/3, he really was the one who dictated Real's game. He may have had a few bad games but overall he was one of the top performers. He has the vision and when he's deep he also as the time to distribute even when he's pressed. I didn't see many Croatia games but maybe was he too high on the pitch ?
As for Di Maria, he's linked to PSG so if he leaves, he will free some space in the midfield (though is usually a right winger and played (very well) the left midfielder when Ancelotti switched to 4/3/3) but IMO, it's not enough. Is Alonso leaving as well ?