There has been a push on the part of STAR to have all members participate in the miles upgrade program. However, the requirement to pay a full Y fare will result in little erosion of inventory for elites. We would still have SWU/NAU upgrades at time of booking on Latitude fares, and I doubt many non-elites expecting to upgrade will pay the steep difference between T+ and Latitude. Other STAR programs also require upgrading only from full fare for non-members, and even those letting members upgrade with miles have introduced copays which pretty much convert a low-fare into a high-fare before sucking off almost as many miles for the upgrade as an economy award ticket to the same destination. So I doubt if this move will take more than a seat or two max from R inventory, and AC still reserves the right to control those allocations.