Which is why it makes even less sense.
The 9900k almost has a point (though an expensive one) in that it's 5-10% faster than AMD in gaming. The thing is? adding two cores will not make it faster in gaming. If anything it will make it so much hotter that it throttles more and is thus slower in gaming and uses more power.
This is why AMD never bought Magny Cours to desktop (12 and 16 core Piledriver) because there was just no point. They just carved on with cheap 4 6 and 8 core CPUs.
And like you say, how are they ever going to compete with the 3950x? which will also no doubt drop in price as it has already (by about £30 since I got mine).
And a whole new socket and thus board? at least AMD stick to the same boards for a while.