TBH we should have done this when Crossfire and SLi first arrived. We know now that scaling is good (up to 100% on Crossfire) so why we still have single cored GPUs is a mystery, when we now have like 40 core CPUs.
Having said that I don't think Nvidia have much of a choice. Navi works the same way, and Navi will inevitably end up in the consoles so the games will go in that direction with or without Nvidia.
The only thing that kinda annoys me is that these will be tiny little dies which are five and ten a penny to make, yet I know they will find a way to big it up and make it sound incredible and charge the earth for it.
It was a cracking idea by AMD, that's for certain. They are frugal with stuff like this and not wasteful, so the more working dies you get per wafer the less you lose.