I now receive a block of IPv6 from Comcast. I allow the router to assign them to devices on the network, but I admit that I am somewhat worried that my local PC is no longer isolated from the Internet by a private IP.
My mum's boring broadband connection, with a free router supplied by the ISP in the UK, has the functionality next to the port forwarding settings for IPv4.
That's typical. Look up IPv6 pinhole to see how ISPs document it.
But I wonder, is it a fair assumption that the router that you get will either 1) not route IPv6 at all, or 2) route IPv6, and by default deny incoming traffic? Problematic would be ones that routed IPv6, and by default accepted incoming traffic.
Second, you get the same security benefits by having a firewall that denies outbound connections not already established.
I'll take an insecure device isolated at the bottom of the ocean in a titanium block over a probably-secure device that is publicly addressable any day.