People keep coming up with that comparison...erm Basti???
What about Schweinsteiger? His case is not in the least comparable to Müller´s and says nothing about the chances of United getting the latter.
Schweinsteiger enters the last chapter of his career and was very vocal about his wish of playing abroad once in his career. His former club repected that wish taken the contract situation and his many years of service into account. It was more out of respect that the club agreed to let him go. The emotional loss clearly outweighed the one on the pitch in this case.
Müller on the other hand might not even have entered his prime at this point, is an absolute key player, consistent top performer and the most valuable marketing figure of the club. His departure would have an immense impact on every level.
As a whole the Müller deal is way harder to pull off than the one of Schweinsteiger, because the club would be way more reluctant to let the former go. Its kinda like saying Schalke had a chance of signing Ronaldo when Raul joined them for two seasons (thats rather harsh to United, but you get the point).
The difference between Scholes, Giggs and Schweinsteiger is that the first two appearantly had no great desire to play outside of United and on the continent at one point in their careers. Would be interesting to see how United would have reacted if those two expressed that wish in the last years of their careers.