as near as I can tell ATI (AMD) is moving away from proprietary drivers, not towards them.
Nvidia has always been proprietary and seems to have no interest in budging
so if Intel is moving from open to proprietary the score is one moving each direction and one standing still. hardly a decisive movement in any direction.
if Intel is in fact not moving to proprietary drives (and given their history with linux and involvement with X.org development, this would seem like an odd thing for them to do), then the result is two of the big three moving to open drivers, and one staying with proprietary drivers.