Maybe. In the alternate reality, we probably would have the same threats on the internet as we do today, and the same boneheaded software that misconfigures things, so my guess is that we’d still have consumer firewalls at the gateway that just default-deny everything. Maybe there would be better standards about auto-configuring these firewalls though. (Or maybe the standards we already have would have just been better supported?)
But for certain, today if we had IPv6 everywhere, it still wouldn’t let you design something like a VoIP phone (or a pure peer-to-peer version of FaceTime) that just listened for connections and let other people “call” you by connecting to your device. That software would only be usable by people who know how to configure their router, and that doesn’t make for very good market penetration. You still need something like UPnP, so you’re basically right back to where we are today. At least the connection tracking would be stateless, I guess?
But for certain, today if we had IPv6 everywhere, it still wouldn’t let you design something like a VoIP phone (or a pure peer-to-peer version of FaceTime) that just listened for connections and let other people “call” you by connecting to your device. That software would only be usable by people who know how to configure their router, and that doesn’t make for very good market penetration. You still need something like UPnP, so you’re basically right back to where we are today. At least the connection tracking would be stateless, I guess?