Saturday's FA Cup final is likely to be Maguire's last game as a United player with the 30-year-old captain set for a place on the bench against Manchester City at Wembley.
Maguire cost £80m from Leicester in 2019 but is now valued at closer to £30m due to his age and the fact he is two-thirds of the way through a six-year contract.
Maguire has another two years left on the £190,000-a-week deal, and it's anticipated that he would earn only half that amount at a new club - leaving United to foot a £10m wage bill to get him off their books.
Maguire has started just 16 out of United's 61 games in all competitions this season with manager Erik ten Hag preferring to play Lisandro Martinez, Raphael Varane, Victor Lindelof and Luke Shaw ahead of him in central defence.
England manager Gareth Southgate warned last week that Maguire's lack of first-team football at United cannot 'continue forever' if he wants to hold down an international place.
And Ten Hag spoke about the player's predicament on Monday, admitting 'that no-one would be happy with this situation - he is not as well'.
The United boss says it's up to Maguire to make a decision about his future, and club sources echoed those comments on Wednesday night.
They insist the Yorkshireman is not being forced out of the door and could yet stay.
Maguire is one of a number of players facing an uncertain future at United after the Cup Final with question marks hanging over Anthony Martial, Fred, Scott McTominay and Aaron Wan-Bissaka.
It's already clear that Phil Jones, Eric Bailly, Axel Tuanzebe, Alex Telles, Brandon Williams and Ethan Galbraith will go.
Dean Henderson has also been lined up for a permanent move to Nottingham Forest if David de Gea signs a new contract at United. Henderson spent this season on loan at Forest but is currently out of action following surgery on a thigh injury.
United must decide whether to keep De Gea's current No 2 Tom Heaton, while Jack Butland will return to Crystal Palace following his loan spell and is in talks with Rangers.
After Diogo Dalot signed a five-year contract on Wednesday, De Gea is expected to be the next United player to agree new terms which would see him earn less than his current £375,000-a-week salary but with more incentivised bonuses.
The Spanish goalkeeper was pictured trying on the club's official Cup Final suit designed by Paul Smith in dark blue.
It came a week after Sir Alex Ferguson had a dig at Liverpool's infamous white suits from their 1996 Cup Final defeat to United when he spoke to Sale Sharks before their Premiership Rugby final against Saracens.
However, United sources insisted that the suits are a very different shade to City's light blue kit - and also pointed out that United wore dark blue when they beat Benfica at Wembley in the 1968 European Cup final.