There's a hell of a difference between drifting on the flank and being a winger. Inability to understand the difference to that is what saw a decline in Dybala's performance throughout the past years in the same way we've seen Rashford struggling when he was placed in that same situation.
Now lets say we buy Dybala and Bruno. Bruno is best utilised as no 10 just behind the strikers. Play him as a LW or as a CM and he'll become less efficient (ex at Sampdoria). Dybala is either a shadow striker or a striker. At best he's a trequartista. Similarly to Bruno he can play in a different role but he'll start losing his efficiency. So how on earth can we fit them both?
Well in my opinion, we should look at our forward line first. We've got Martial, Rashford, Sanchez, Dybala and Greenwood there aka strikers who drift on the flank. As said, Bruno is most suited as no 10, while Pogba is most suited in a 3 men CM while partnered with a box to box midfielder (Vidal at Juve/Mctominay at United?) and a Pirlo type of player. We don't have that guy so Matic will have to suffice. Considering how flanks kind of suck (runner from the championship, Jesse, Mata, Young, Sanchez whom btw is more comfortable upfront) then Id guess no one will really miss not having wingers.
Now lets have a look at defence. We've got two FBs who are defensively sound (Shaw and AWB), hopefully we'll sign a CB and we've got Lindelof. That should, on paper, be a solid defensive unit which is good enough not to need being helped by wingers backtracking.
So how should we play? Id say a diamond 4-4-2 system is the answer.
Defence: AWB-----Smalling-----Maguire-------Shaw. Its a hell of a solid unit, with AWB/Shaw closing the flanks and Smalling + Maguire winning any cross coming their way. Maguire will be the brains, Smalling will provide the pace alongside AWB.
Midfield: Matic will conduct the orchestra from the back, bringing more inches in the CB if we find ourselves being bombarded by crosses. Pogba can easily play as mezzala, a role he covered superbly at Juventus. He'll be doing what he does with us while keeping an eye to the Left flank. Mctominay will be a more hardworking/less talented version of Pogba on the RCM side.
FWD: Bruno will play as no 10, exploiting the spaces left by Dybala (Right sided striker) and Rashford (left sided striker). Meanwhile Rashford and Dybala will be strikers who'll help up the flanks when defending while moving swiftly to position when attacking. Its similar to the system Juventus used against us when they won 1-0 (Dybala goal)
So in defense we go in a 4-5-1- formation with Rashford and Dybala helping on the flanks & Bruno acting as a false 9. When attacking it goes into a diamond 4-4-2 system with Dybala, Rashy and Bruno bombarding the defence.