So first off, I think it’s safe to assume that the article is not about going and removing IPv4 on your company’s corporate networks for a month, so I’ve been speaking in regards to home internet service.
NAT is not a firewall, but in normal use by the average home internet user it is a means to prevent computers outside of their network from reaching computers inside the network without ports being forwarded on the router, or the internal machine initiating the connection. If you do not have a firewall on the devices, and they are not behind a NAT gateway/router, then they are by default exposing ports. There’s no inherent guarantee that a router has a firewall configured properly, or has it enabled.
I’ve never seen NAT in combination with IPv6 and I’ve seen plenty of deployments at our customers.
I’m interested in how this works. In a normal IPv4 scenario for home internet users, you are assigned a single IP for your router by your ISP, and internal addressing is usually handled by router-resident DHCP automatically. In the deployments you’re seeing, are ISPs handing out /120 blocks to each router? Does that require the ISP to have access to alter your home router, or do customers configure the DHCP themselves (which seems unlikely to scale)?
Thank you, this is super informative!