If Jose wants Dier, it surely means he's going for the Champions League as well. Maybe not yet this season but for the near future, absolutely yes. It might take some time but i can finally understand what style of game Mourinho wants this United to play.
Most people don't know a couple things about Jose. One thing is that he is, in fact, an experimentalist, when it comes to tactical systems. People too often associate him to defensive football, when in reality, he has been changing styles between every team he has managed, sometimes even during the same seasons. I could give you the practical examples but i'm rather lazy right now. The truth is, Jose's tactical system has been transforming, and to a degree, being cooked and developed. But during all those spells and since the start of his career, he has kept some stuff constant, which is the massive desire to win. Like cracking a Virus, or unlocking the most success ratio through complex systems.
The other thing is that most people are unaware of Mourinho's sense of honour, despite looking like a cnut sometimes. So it's fair to say he will not disappoint true United fans. Since i'm some kind of a humble tactical guru i can also tell you some details, if this deal goes through, like you should expect a very physical team in all places. Defending as a unit composed of athletes of superior capabilities, that can overpower and/or outsmart opposing attackers. And also physical in a sense that the team does very quick transitions, be them attacking or defending. Higher speeds in all team means overall off the ball movement is quicker. The attacking will be a false nine that links very well and leaves opposing defenders in check with his prowess. Just right behind, a mobile and vertical 10, just like Anderson Talisca (another signing i suspect will be made) that can score goals and drag defenders with vertical movement and excellent off the ball capabilities, coupled by two marauding wingers ready to timely burst into 1-2s and quick combinations with the 9 and the 10 but also with the fullbacks and other mids (Pogba roams around the more attacking 10, and links well with wingers and false 9, with his fabulous close control skills).
Dier slots in as a holding defensive mid. Him or someone else with a little bit more pace to grab those dead balls when both Pogba and the 10 are too balanced in attack. I still think Danilo Pereira would be better for that.
Cheers