It is relevant if they are keeping a disgruntled player who may not be at his best.
How does that go then?
United; 'We want Grealish.'
Villa; '£80m.'
United; 'What! Nah, we can't pay more than £50.'
Villa; 'You paid £80m for Maguire and £50m for Wan Bissaka last year. Both are defenders, Jack is a creative attacking midfielder and was one of the best in the league last season.'
United: 'But we bought them to be starters, and we got Bruno for £50 so we won't be paying more for his backup.'
If Villa go to Grealish with that, you really see him kicking up a fuss at not getting the chance to go to a team that clearly doesn't want him that much?
He did it in the Championship. His success in the EPL was as a left-sided attacker. I don't see how bringing him as a Pogba replacement makes sense. He has nowhere near the passing range of the clear link guys you mentioned, especially when you are talking about arguably two of the best midfield passers of the past 30 years in Scholes and Xavi. Pogba is mostly used not only as the link but to sit back and hold with more defensive responsibilities to clean up for. My point is, why is Grealish the ideal link to play those roles. A lot of times our formation turned into a 4-2-3-1 essentially. If you are paying a fortune for him, atleast use him tactically in the way he's been used this year, which is as a left-sided attacker. If the option is buy Grealish as a replacement for Pogba's role or don't buy him, I wouldn't buy him. There are much more proven players at higher levels at that role if we are going to be throwing around 60m or so on a #8 midfielder.
He spent the vast majority of his time in the Premier League this past season operating from the left, yes, but that is not the only role he excels in. He is 24 and has been playing senior football for, what, six years? His versatility is well established and, given the season he's just had, there are no concerns about him playing at this level. If Ebereche Eze was to move to a Premier League club this off-season and similarly thrive playing off the left, there would be no doubting his ability to play as a no.10 in a top league, as it has already been shown that that is one his positions.
If anything, the consensus was that Grealish had had his best season to date when moved to, and then playing consistently as, the left-sided no.8 as opposed to being used as more of a no.10 or on the left wing. There is also the circumstances of the club to consider - Villa looking to gain promotion and having the onus on them to be proactive and win games is much closer to the situation he would find himself in were he to sign for United than battling relegation and being in a much more reactive side. His best in the former scenario has come from playing as a no.8.
I only mentioned Xavi and Scholes to illustrate the kind of positional freedom you get in that role. The particular style of the player isn't terribly important in that sense, with players of varying strengths and tendencies having operated in that area - Essien or Khedira, for example. Others who are comparable to Grealish in the sense that their game largely revolves around carrying the ball to evade pressure or progress the play would be Dembele or even Sissoko at Spurs, Wilshere, Rabiot or maybe Arthur Melo.
I wouldn't say Grealish was the ideal Pogba replacement so much as one of quite a few potential options. A Pogba replacement for me could either fit in as the no.8 next to a no.6(Matic) in a deep midfield pair in a 4-2-3-1, as the deeper of two no.8's (with/behind Fernandes) ahead of a no.6(Matic) in a 4-3-3 (a very minor tweak) or as one of two no.8's with equal license to attack ahead of that no.6.
It is obvious that you don't consider the latter an option and I agree that it would require a change to the team shape so is perhaps unrealistic. City have used a rather extreme example of this setup very successfully prior to Fernandinho being replaced, but Lazio and previously Leverkusen have used two attacking no.8's in a more regular way to good effect as well as Leicester and Real Madrid. If Solskjaer was inclined to use this shape he would likely be doing so now with Pogba clearly capable of playing with more freedom or responsibility for getting forward. We could, however, identify a particular player as a replacement who is stronger, or who you would only really want to play, higher than Pogba is now. Maddison, Milinkovic-Savic, Havertz, Brandt and Draxler are examples. Bernardo Silva and probably Foden too - unlikely targets but at least one of them will surely be disillusioned at not being seen as the David Silva replacement. Van de Beek also would really only excite me as a player with the freedom to 'go' - to get forward, identify spaces and interchange with teammates.
The former two shapes are virtually interchangeable - the typical difference between being a holder, an advanced midfielder or the link in between in a 4-2-3-1 compared to a 4-3-3 is negligible for the majority of players. Thiago, Alaba, Rabiot or Fabian Ruiz could be options here perhaps (though how likely is it any would want to come?).
Aouar and Luis Alberto would fit into any of those configurations, as would Grealish. I think with any of those three you would tweak the current shape so it was more of a 4-3-3 with the new addition as the deeper no.8 to maximise the use of the three players involved, something which you would not do with Thiago or Rabiot for me. Unsure on Alaba and Fabian Ruiz. Who else do you see as options? Who is the 'ideal' Pogba replacement?
I think its justifiable to bring him in at 55-60 mill. as a rotation option. We have all seen what happens when Bruno is playing all the minutes. If Grealish gets 30-40 minutes each game , Bruno will be so much more consistent.
I just can't see how - that's £55-60m that could be spent on a first choice pick.
The thought of De Gea, Lindelof, Wan Bissaka and Matic playing every minute is a far bigger concern.