They don't need Blu-Ray. The console doesn't need to play HD movie discs to be succesful (Wii). All it needs the new format to do is play games. Right now with Netflix HD, streaming, downloads, etc. they are satisfying any HD movie needs. They still can't play HD movie discs right now past the old HD-DVD's and yet it is still a great console and selling more than the PS3 by a wide margin. Not to mention by the time of the new consoles, if Blu-Ray is vastly adopted, its price will be much lower, so much so that a new Xbox + a Blu-Ray player will be cheaper than a PS4 with Blu-Ray included. Kinda like how a Gamecube + DVD player was cheaper than Xbox or PS2.
Considering most of your post was unbased speculation, what if PSN isn't free anymore on the new system? Surely Sony won't want to lose all that money all over again. If the next Xbox does not include an HD movie player option, it will be available for cheaper, and with the streaming and downloads, still appeal to most people (as broadband speeds and reach will also be vastly expanded in 4 years, although I expect the next Xbox will be around in late 2011).
