Why should he quit? with man u he's won 8 prem titles, 5 fa cups and the european cup. Winning the league and fa cup double twice and the treble in 1999. He can probably go on for another 10 years at least and still put a few more trophies in the old cabinet.
Jusdt think of some of the fucking world class players that've played for him over the years, and the ones he's sold when they've pissed him off lol
