No, I would gladly sell him to Juventus for 30m but any price other than 70m to United would be awful. A destroyer in the Matic mould is exactly what they need. Mourinho isn't interested in controlling the tempo of games in possession (like Veratti would do) and dictating the midfield is the job of the 85m player they bought the other summer. Last season one of the problems they had was the Pogba wasn't able to use his full attacking prowess because he had to be a bit defensive-minded since there was no out and out destroyer to lock down the games. Matic on the other hand, in his favoured DM role, is perfect for this. He's poor in a 2 man midfield but when we played 3-5-2 at times he had less space to cover but could lay off the ball to others to go on the offensive. Pogba/Herrera/Matic is scarily dangerous especially with somebody like Lukaku to convert all those chances that Ibra constantly missed last season. Matic is big, strong and a very good reader of the game so he'll be good at trying to secure the back / midfield, Herrera doing the dirty work and Pogba having a completely free role in the offense. Man United fans are clamoring for Fabinho but there is a reason why Mourinho hasn't lodged anything for him when the player has even said he wants to join.
I worry that we won't even get in a decent replacement and ultimately with this just further raises my anxiety (which was nicely put by Scott Harris / Carefree in the other thread). In fact as a separate note I have no idea if Bakayoko has the necessary qualities to augment our midfield (or Rudiger over VVD or Christensen...)