[lmm]

We'll never run out in the sense that it will always be possible to buy one if you have enough money. Just like we haven't "run out" of, say, original Apple ][s - if you really want one, and can pay enough, you can still get them in the open market.

Doesn't mean they're available at a practical price for most endeavours though. At some point it's going to become cheaper to use IPv6 than to buy from the limited pool of IPv4 addresses. Indeed for some use cases it's already there.