The IPv6 Transition

I'm pretty naive about this stuff, but IMO IPv6 is a lot more empowering than v4. You aren't dependent on some owner of v4 addresses for access, you don't need to manage--and aren't forced into--NAT, and you (probably) get to use all of your ports.

My conspiracy theories about why v6 hasn't taken off are: people make money off v4 leases, and email spam blacklists become pretty useless in v6. But again, very naive here.

The more likely reality is that we have a lot of v4-only hw in place with lifespan of 20+ years. Those devices won't go away.

Heck, I work on embedded, and having a dual-stack system is just a PITA to deal with. If v6 would have been fully retro-compatible this wouldn't have been something to think about, but you can't drop v4 and there's no future in sight where v6 will be the only choice (we'll have dual-stack for a looooong time), so we just push the problem up the chain.

There are plenty of systems being developed _now_ which are still v4 only as a result.