Let's be honest, If Maguire live Manchester United, he is as good as gone, they even thankful that West Ham made an attempted with good offer; who in there right senses in Premier League will want to have Maguire in such a big amount, an increase in performance and seasonal goals is equivalents to high amount and for the past two seasons, Maguire has been robotic player in my opinion, they either reason with West Ham to increase the Bid a little and sell him or they accept his entertainment continuesly, it's up to them.
With his current condition, actually the price of 20 million also I think it is very good for Maguire

Maguire's condition is getting worse and worse at Manchester United and when he is given the opportunity, he is like a player who sides with the opponent lol.
I think he really has to try something new at a smaller club because to be at a big club like Manchester United Maguire is quite difficult actually and his performance is very different from him in Leicester uniform.
But talking about West Ham's offer to Maguire it seems that it has been rejected by Manchester United because they want around 40 million for the player. But with the performance he is showing now it is actually like a dream if you want interested clubs to pay 40 million for Maguire.