It's not the official word. In fact, this is a Marca report, so take it with a grain of salt, as usual. But anyway, according to the Spanish paper, Carlo Ancelotti would be thinking to clone Di María's role in last season's 4-3-3 with Fábio Coentrao, whose versatility was tested during the 2011-2012 campaign in which he started playing alongside Xabi Alonso in Mourinho's 4-2-3-1.
That did not work as expected, but it's true that it should be a bit easier for him to adapt to a three-man midfield in which he wouldn't have as much presence with the ball. Coentrao would be a box-to-box midfielder in order to help Toni Kroos and Luka Modric defensively.
Still, Real Madrid would be losing their best left back on the roster. Marcelo hasn't been shining over the last couple of years, and it would be surprising to start both of them when Real Madrid have no more backups for that position than some occasional starts by Nacho Fernández. That's why it would make so much sense for Carlo Ancelotti to start either Asier Illarramendi or Isco Alarcón. While Illarra would be the one playing deep and letting Kroos and Modric get to the attacking third of the field, if Isco starts Kroos would be the the last man standing in front of Real Madrid's defensive line. The German was superb there against Sevilla in the UEFA Supercup, but he might still need some time to learn the position in order to provide a solid defensive effort.
One way or another, both options would be far more natural and comprehensive than Coentrao or Varane playing in the midfield. Illarramendi and Isco might still be green, but Ancelotti and his coaching staff have no option but to trust them after Real Madrid's moves during this summer transfer window.