here's the thing- Blu- Ray movies do not output at 720p. They work at 480p, 1080i and 1080p. If your tv does go to 1080p as you say the movies should work at that. Go into the PS3's video output options and make sure you have the 1080p option selected. Movies are still 24 frames/ second so there should be no problem there.
It's no surprise that the low-level tech support at the phone number doesn't know- they are given stock responses for certain situations and that is about it. they aren't in the know about things coming in the pipeline. Right now any talk about a fix is just that- talk and wishful thinking from various forum goers.