<Have you heard even a hint of adoption in any other device, from any manufacturer? >
It's safe to say the new cards are not made in a vacuum. CF cards are faster than SD, and XQD is much faster than CF. Frame rate and write speed are very important to some markets - and there has not been a significant move forward in some time. Nikon has made a step with the D4, but you can bet that's not the only step. Lexar has been talking about XQD for some time, but is just now announcing products.
Given that the Sony cards of today are first generation XQD, it makes sense that they will continue to get faster like the previous SD and CF cards. XQD opens up a new level of performance - and that will make it pretty hard for Nikon and Canon to miss the performance in cameras that require speed.
It's hard to get a true comparison of card speed based on specs. But the tested speed of the Sony card is 50% faster than the fastest CF1 card, and the Lexar XQF cards carry a spec that is 30% faster than Sony - which would be double the speed of their fastest CF1 card.
An announcement from a camera company would require a new body. Nikon appears the closest with a higher speed version of the D4 - or the same speed with larger files. Canon has been the speed leader and they won't be sitting back with nothing in design if Nikon is coming out with cameras that can use XQD speed.