I actually think this could be United's year in the CL. Bayern and Real Madrid are choke artists, Barcelona look uncharacteristicallt vulnerable, Arsenal doesn't have the defense, Ajax and the other smaller league teams don't have the quality and City and Dortmund don't have the experience.
I think United are just good enough to get through, so long as they dont run into Barca. If some other team can pull off a lucky win over Barça, United has a legitimate shot. Chelsea could be contenders as well.