Broadly called it:
I'd love this. Updated hardware every 2/3/4 years, with a guarantee of a minimum 6/8 years support for all titles, with some games offering more (I'm talking EA Sports here). Ideal world, they'd require that all games run at a minimum resolution / framerate on each piece of hardware - 720p / 30fps for Xbox One, 1080p / 60fps for Xbox Two etc., but I'm not sure they have the leverage for that right now. But a measure like that would help alleviate the very real concerns of people buying older hardware, that they'll be receiving really substandard down-ports.
But yeah. On the surface, it looks like a lot of the benefits of PC gaming (endless backwards compatibility), with less of the drawbacks (high entry costs to run the AAA games, and no guarantee of future compatibility). Count me in.