i doubt any disc based media format is going to succeed. we're moving to a flash memory based era. i see one of two things happening.
1. (more likely of the 2) everyone moves to an internet download based movie purchase and rental. all major players start producing ready out of the box HTPC style players that play all downloaded content for you.
2. (maybe a transitional change before #1) movie purchases and rentals use some sort of flash device, in order to rent and buy movies. these usb style devices are plugged into your HTPC style player and played directly from the device.
i wouldn't bother with blu-ray, it's just not going to be around long enough. the real limiting factors right now seems to be knowledge building HTPCs and home internet connections. as soon as the major players (Sony, Samsung, Denon, etc) start making HTPCs, and our home internet service reaches new standard speeds that everyone can afford... the portable disc based media content we know now will be dead.