Is the FX revolution fizzling?

Not at all. I think:

Nikon probably should have come out with the D600 first - SO many people buy into the "highest number of megapixels is the best and what I must have" (irregardless of how big they print, their needs, skill level, etc) that the D800 sucked up all the megapixel envy photographers who have been waiting for years and years while Canon had 21 mp with their 5d-ii. Thus a lot of people for whom a D600 might be a better fit have a D800. But the D600 came out after the 800, and while it's selling, it's still a fairly expensive camera in the grand scheme of things and doesn't have that groundswell of customers who were waiting for the first reasonably priced high mp model from Nikon to come out to help it out.

As for Thoms conjecture that the D800 goes away and the D800E remains, I tend to doubt it, although I think Nikon (and others) were surprised at how many people got the E version.

-m