The question is, how will you obtain that IP address from them? DNS was the answer to that question. So when you ask that question again, you're effectively asking for a DNS alternative.
I mean, all of this is a hypothetical, but wouldn't you find the IP in the same way how you'd find the domain now? If there's means among communities to disseminate new TLDs as these websites are forced to move back and forth, then there's nothing stopping them from sharing IPs instead.