I would not have bought my PS3's if there was a cheaper br standalone available, assuming the standalones worked correctly (which many of the current ones still don't). Most of the crew I hang with would likely have done the same, as we all bought PS3's as movie players.
However, Sony would then have lost any chance of potentially earning revenue from us in their other ventures that work on PS3. Take games, we don't buy many PS3 games now, but who knows maybe someday we will. Likewise, if they offered downloadable movies someday, or some other services, that's more money permanently lost from us since our standalones can't do that kind of stuff. In either case (standalone or PS3) the bluray related royalties earned is the same, but standalone hurts them in not being able to receive other sources of revenue from us.
So...if they have to choice subsidize something, don't you think it would be better if they subsidized PS3's instead of standalone players? Standalone players seem like a dead end to me. They serve a purpose, but they don't really advance Sony towards being the multi media device standard on peoples tv's, which is where the big bucks are at.