[blahedo]

> This seems to have been rumbling on for some time now - at least for the past five years or so. ... It's not like it's been an overnight thing.

To say the least! This particular rumble ("we're out!") may be new-ish in the last few years, but the general rumble ("we'll run out!") has been going on a lot longer, and the transition is pretty much the opposite of an overnight thing. I learned about how IPv6 was imminently needed and right around the corner when I took a networks class in college. In 1996. Tanenbaum's book (from four editions ago!) includes ten pages on IPv6 that could appear in a book published today nearly unchanged.