My guess is it will be a small percentage of MVPGs who have been identified as flying an insane amount of BIS miles on AS metal and/or have a spend level of a predetermined and as yet undisclosed dollar amount with AS.
Bingo. That was the impression I got as well.
As for United Global Services, basically, it's a way for UA to reward people who are top revenue at UA, as opposed to the 1Ks who fly on 2.2 cent per mile mileage runs so they can burn upgrade instruments to upgrade their SFO-SYD/FRA/SIN trips.