Which is why I said 4bn, with investment pledges. And that was on a club that was practically put on sale by force. Man Utd would require its valuation + debt clearance and on top of that whatever the Glazers would want for potentially lost profits. When that is all well and done there would also be a need for significant investment into the stadium and fascilities of the club.
At 3.7 bn valuation, the minimum price is 4bn - given that the club could be valued significantly higher in 5 years time - there is no way they are accepting a low ball offer of 4 bn. The brand is still very strong, the club's revenues are not dropping significantly and we remain one of the richest clubs in the world - despite being unsuccessful on the pitch. With the new TV deals in the US coming into play, an increasing market presence globally. The club's valuation will only go up.
The debt is a red herring as well. 500M debt on an asset currently valued at 3.7bn is not a lot. Most of the debt is on fixed interest, so interest changes are irrelevant. We're not over-leveraged.
The Glazers reportedly believed a 7bn valuation was well within the club's potential just a year ago - the Chelsea sale will have increased that belief. They flat out rejected the Saudis offer of 3.8bn. Negotiations went no further, likely because the Glazers at the time wanted closer to their prospective 6-7bn valuation. After the Chelsea sale, it could well be higher.