While Pogba is great player on his day, he is still luxury player that can work only in the team that is fully balanced where his flaws can be overturned by quality of players around, or level of competition. Pogba did good for Juventus, but Juventus had bad rivals around in the league, and in the CL he did not make an impact they wanted. In France, you are always playing with great squad around, while also against teams that are tactically not prepared enough for high pressing game. In the World Cup when teams on the higher level he was good, but not in all games. It can be up to motivation.
So, at the moment in United, as he is a luxury player question is does he deserve to play above Bruno in free flowing position? Would not say so, even when he did he never produced numbers similar to Bruno these days. If not, can we play him behind Bruno and be world class in that position? Have not seen that from him in the past on regular basis, yes from time to time. So, I would say you can find better players to play in two man midfield, behind number 10, or even in 4-3-3 midfield position.
Add to this injuries. Every October/November is the same. Pogba out for who knows how long, few weeks, or few months. Travelling around the globe in that time for whatever reasons.
Add to this his PR team, agent, brothers, making PR mess wherever and whenever they can.
Bottom line, do you think Aston Villa would take him in swap deal without money for Grealish at the moment? Not many teams would take him and he would not improve them which is the reason why they would not take him.
Unfortunately, I don't see we can sell him easily. He is 18 months away of leaving for free and taking all the money to his and agent pockets. To me it looks like money is all he and his team are looking at, so I think he will not leave the club until he is free to go. He will try to blackmail club to get new big deal to stay, while Glazers won't allow for him to leave for free and will sign whatever crazy deal he wants that will distract dressing room. I can't see positive solution for us in that case. At the moment, looks to me that he should be deployed as good sub, especially when there is enough space on the pitch, when we are goal or two up, to rest Bruno, or someone in the midfield. And that is it for next period.