We are running out of IPv4 addresses.
Although it would take a while until we completely run out of IPv4 addresses to develop new services and applications, the shortage of IPv4 addresses is evident. IPv4 addresses are becoming harder to get and more expensive.
Obviously, IPv4 still runs most of our networks, but in long-term technological development, IPv6 will be the only solution. IPv6 is already starting to fulfill its mission: to deal with the lack and exhaustion of IPv4 addresses. 
What’s the problem with IPv4?
The first formal standard of IPv4 (our beloved Internet Protocol addressing and identification scheme) was created in 1980. It only took some years, when in the late 1980s, computer scientists were already predicting that by the year 2000, we would use all of our IPv4 addresses.
There were four billion IPv4 addresses in the pool at our disposal. So why should we all run out of IPv4s so quickly?
Technologists at that time knew there was incredible technological growth. The demand for IPv4 addresses was growing out of control.
Necessity pushed a few brilliant minds to devise temporary but magnificent solutions to this depletion. Solutions such as NAT (Network Address Translation) and CIDR (Classless Inter-Domain Routing) allowed us to use IPv4 for a few years longer.
But fast forward to 2022, and many more factors contribute to this inevitable and painful IPv4 address exhaustion. NAT can’t simply keep up. These factors include the expansion of services, applications, and infrastructure that loves IPv4— IoT, virtualization, cloud, and containers, which are a few examples.
The only solution to a long-term problem.
For now, it’s true; the only solution to the long-time problem of IPv4 address exhaustion is a migration to IPv6. In fact, scientists created IPv6 addressing scheme to solve this IPv4 exhaustion problem.
IPv6 not only provides a mind-blowing number of addresses (340 trillion trillion trillion IP addresses, to be precise) to tackle this problem, but it also provides new services unavailable in IPv4. Aside from these, there are many differences between IPv4 and IPv6 that many people don’t know, but the most significant difference is that IPv6 could be virtually endless, so it does not need NAT.
Other significant differences are that IPv4 and IPv6 have entirely different address notations. One uses decimal (IPv4) and the other hexadecimal (IPv6) to expand the number of combinations. This results in longer and more complex IPv6 addresses, so IPv6 introduces shortening techniques that can shorten these addresses (something unavailable in IPv4).
Other good distinctions of IPv6 are its built-in IPsec, IPv6’s multicasts, anycast, and more. Just like these, more improvements make IPv6 a sweeter solution for long-term technological advancement.
So, what are we waiting for? Why don’t we fully embrace IPv6?
One of the biggest reasons we haven’t fully transitioned to IPv6 is that we still have IPv4 space available. Although IANA (Internet Assigned Numbers Authority) literally ran out of IPv4s, as they sent out their last five portions (of 16.7 million) to the five Regional Internet Registries (RIRs)- the RIRs have done an excellent job reserving IPv4 addressing space. RIRs are intelligently recovering and reserving IPv4s. And whatever limited IPv4 addressing blocks they would provide, ISPs and LIRs can use methods like NAT to expand those number of addresses.
Another reason we haven’t fully migrated to IPv6 is that most of the Internet still works on IPv4. This means most of the Internet’s infrastructure uses IPv4 addresses; legacy applications run on IPv4, and multi-purpose servers and mobiles still use IPv4. And this is without counting the brownfield devices that only support IPv4 (which is a minority now). Incompatibility with IPv6 plays a significant role in this developmental delay.
The costs could skyrocket for anyone investing heavily in new IPv6-compliant infrastructure or buying IPv4 address blocks for the migration. However, the key to overcoming this incompatibility to IPv6 and wanting to evolve to IPv6 is a slow but steady migration to IPv6. Leasing IP addressing space instead of buying it (buying vs. leasing an IP) can help transition to the next IPv6 phase.
The proof that we are all already on the IPv6 path.
Although it has been a slow process, we are already adopting IPv6 as a core addressing and identification scheme. Most early adopters are already using dual-stack services (where IPv4 and IPv6 are used simultanously) which turns into a positive long-term technological advancement.
IPv6 adoption rates are increasing quite quickly. According to an IPv6 Google statistics report, on January 2020, about 29.5% of the global users accessing Google used an IPv6 connection. And now, as of October 15, 2022, approximately 37.17% of the total users accessing Google worldwide used IPv6 to connect. 
On this same report, you can see that countries like India, China, the United States, Finland, France, Germany, Belgium, Canada, Mexico, the UK, Brazil, Saudi Arabia, Japan, Malaysia, and more, have quite high IPv6 adoption rate. In addition, the users in these countries have very low impact and latency while using IPv6.
Countries like India, with large populations which faced a massive growth in mobile communications had to devise ways to share public IPv4s (through Carrier-Grade NATs – CGNATs) to save some IPv4 addresses and connect many people to the Internet with one address. Countries like India, South Korea, Japan, and China had to take the IPv6 path, as a temporary solution like CGNAT was not enough. Now India is one of the leaders (after France) in IPv6 adoption, with a 66.6% adoption.
The proof is not only in graphs and country-wide statistics; you can see yourself with your own devices. Most electronic devices and systems today are built-in with IPv6 enabled by default and ready for IPv6 traffic.
Final Words.
The complete transition to IPv6 will take time, but it is inevitable.
New IPv4 addresses are becoming more expensive and harder to obtain as days go by. To save some addressing IP space and costs, Internet Service Providers (ISPs) are rethinking their IP addressing strategies. They are deploying wide-scale Carrier-Grade NATs (CGNATs) and fully transitioning portions of their networks to IPv6.
Regarding developers and service providers, they are leasing IPv4s (instead of buying) to make cost-efficient transitions to IPv6. And finally, regarding consumers or end-users— their computers, mobiles, tablets, and home networking equipment already support IPv6, so their transition is much smoother.
IPv6 will be, in the long run, the real light at the end of the tunnel.
