Btw, I think the current estimates are that arin will be out of ip4 addresses next year. Hopefully they will crack down on the tier 1s who have been allocating addresses to customers and not deallocating when the customers leave. We had 10+ /24's from a tier 1 that they continued to state were delegated to us years after service was discontinued. I'm sure that's common and wouldn't be surprised if half the addresses tier 1s have are not actually being used.
Once arin is out of addresses, we will likely see private exchanges for ip4 addresses. Luckily most operating systems do pretty well with ip6. The problems are feature parity at the ISP routing level and end user modems/routers. It's just a matter of a few years and ip4 will be that thing we sometimes use, but hopefully don't care too much about.