Oh, additionally FWIW (possibly not much) -- I have an acquaintance who owns/runs a medium to large privately owned ISP in the Chicago area. And his personal spin on this topic is the "lack of IPv4 addresses" is unlikely to ever be an issue. There are so many chunks that people are squatting on, and so many devices being assigned real IPv4 that don't need them.
“Extinction is the rule. Survival is the exception.” -- Carl Sagan