> And yet we are probably multiple decades away from 90% adoption and it is quite possible given the level of coordination required that we may never get to 10

> And yet we are probably multiple decades away from 90% adoption and it is quite possible given the level of coordination required that we may never get to 100% adoption. 100% adaption will never come. Just look how many companies still use COBOL software that was developed in the 70s. The question rather is: when will IPv4 become insignificant enough that your company won't have to care about it anymore?