Even domestic/TB might not be so easy. Although there are a bunch of UA-lovers who hang around the AC forum just to troll those of us who fly AC and claim to have virtually 100% upgrade success, having schedule flexibility to plan flights based on upgradability and having 1K status make that a lot easier. If you're flying for work (i.e. less flexible schedule) and don't have 1K/GS, I don't imagine you're going to clear many CPUs even on TB/US domestic.