United will not be sold any time soon unless someone offers £5b or more. Why would the Glazers sell. It is easy money for them. They poured nothing(in terms of money) in to the club and took out so much, just to pay off something they piled on. As long as the club is on top off the field, there is very little reason for them to sell. It is a cash cow for them.
Also another reason why the club will not be sold is because of the amount of money it will cost to buy the club. Letting go of a couple of billion is a lot more difficult to do than letting go of a couple of 100m. My worry is, the new owner could potentially be worse than the old ones. Due to the valuation of the club now compared to when the Glazers took over, who's to say that they will increase the debt in order for the owner to make his money back when be buys the club off the Glazers. The Glazers have potentially screwed up United for decades to come because of their greed.