Another possible reason we still have IPv4
I just watched a video on facebook talking about why we run out of ipv4. Besides more and more human got online and thus more devices need an ip address to work, i thought of another reason. The ipv4 depletion problem is more likely towards new cloud hosting/internet service providers wanting a pool of ipv4 addresses. For internet companies founded before 2011 (the year ipv4 addresses fully depleted,) they simply sit back, relax, and keep paying RIRs for maintaining their ipv4 pools, because they already own them before ipv4 depletion. And other internet companies refusing to deploy ipv6 is adding more reason to not deploy ipv6 on top of the need to replace a bunch of legacy devices, more hours of training needed, and a patchy hack provided for connecting more devices to internet with just one public ipv4 with NAT. Unless IANA working with RIRs and Tier 1 and 2 networks to fully stop ipv4 from working, we'll still have ipv4 for years to come.