You may be right. At that time we will end up introducing or requiring some kind of horrible port multiplexing scheme, like maybe port knocking (using a patter

You may be right. At that time we will end up introducing or requiring some kind of horrible port multiplexing scheme, like maybe port knocking (using a pattern advertised in DNS) or maybe even... HTTP/1.1's Host: header :) Separately, I think addresses are slightly different than those other measurements. I'd think the number of needed public server ip:port addresses is roughly on the same order of magnitude as the number of humans, or perhaps less. By that measurement, 4 billion is almost enough, but clearly not enough. I wouldn't want to have to bet on that, but I don't have to. There's always another layer of indirection possible. And that layer of indirection will always be infinitely easier to deploy than a replacement to IPv4.