It makes way too much sense to not do this. There's no reason they couldn't get people to commit to the high end of their offering every few years as is done with phones. They have most of the pieces in place with the system architecture and store ecosystem to support it. They just have to hammer into people that this will work just like their phones do to keep the casual crowd from freaking out and being scared off.
I don't see a lot of console gamers willing to enter a console upgrade contract plan.