Intel's "next gen" motherboards are still using DDR3, but then, Intel's "next gen" generally lasts about, what, 6-8 months? AMD hasn't had a "next gen" motherboard/chipset in ages. As for AMD and Intel being "slow to embrace" changing the interface between CPU and memory, when's the last time AMD was slow to embrace change? And you can bet when AMD jumps on the DDR4 bandwagon, Intel will be sure to follow.
Of course, that assumes that they have much choice. I mean, it's not as though Samsung and Micron are known for pushing a new memory spec by saying "Okay, we're ceasing manufacturing of the old spec," or anything like that. </sarcasm>
Obviously, we can expect DDR4 to hit servers first, since enterprise users are more likely to demand faster, lower-power RAM, and less likely to shy away from the higher cost at launch. The question is, does anyone have any relatively solid information (NOT just more crap coughed up by the rumor mill) on when we should expect to see that, and a rough idea of how long after that we might see it at the consumer level?