Sounds too good to be true. All the talk of destroyers, DMs etc but I've always wanted a playmaker at United. Someone with that intelligence and weight of pass. Utterly neglected area.
There's nothing wrong with a DM, but it's not necessarily needed. United need to look at the midfield as a 3, with all the different qualities covered within those 3. How you do it is up to the club/manager. Therefore, a DM could be needed, or not. It all depends on the other 2 midfielders, or as I stated, the collective qualities the entire midfield brings.
For example,
1. Juve in 2013-15 had Pogba, Pirlo, and Vidal.
Qualities: Pogba brought moments of magic, and helped with creation, scoring, adding steel. Pirlo brought creativity from the back, brought a defensive presence by not venturing forward too often (due to legs being gone), and helped spread the ball around. Vidal brought energy that Pogba and Pirlo did not have. He brought goal scoring, and helped defend through his energy. Their end product probably was their best value.
2. Barca - Iniesta, Xavi, and Busquets. All 3 were great at recycling possession. Busquets could break up attacks through anticipating attacks and quickly distributed the ball after winning it back. Iniesta provided dribbling in the final third, and creativity. Xavi was the more constant ball distributor always providing a get out of jail free card to his teammates.
3. Real Madrid - Modric, Casemiro, and Kroos. Similar to Barca with Casemiro being slightly different to Busquets, as well as Modric and Kroos being more of a blend between Iniesta and Xavi. Unlike Juve, do not have such differences in energy, but because all provide more energy than Pogba and Pirlo, do not need a Vidal type player.
These 3 midfields were very different, but still were considered the best at one point (for Barca a longer amount of time). However, if you were to look at providing defensive cover, providing energy, providing ball distribution, providing the safest pair of hands to receive the ball, providing creativity, etc... they all provide that. They just have different types of players who shine together.
As long as our collective midfield is rather complete, with the members providing cover (to varying levels) for one another across all areas the midfield is supposed to provide, what each type is does not matter.