For all of the issues with Comcast, the one bright spot with them is their IPv6 support. They were one of the first to support it well.

Ah, I didn't know that! But it makes sense; their network is certainly large enough.

Well, duh, there's no NAT in IPv6...

A dynamic /64 is still not proper Internet though.

As a residential customer, that would be a static /56 at least :

https://www.ripe.net/publications/docs/ripe-690

> /64 is not sustainable, it doesn't allow customer subnetting, and it doesn't follow IETF recommendations of “at least” multiple /64s per customer.

(Why are ISPs being skimpy on IPv6 addresses?? Doesn't this imply that they will need to do extra work in the future to move those /64 customers to /56 or /48 ?)

> An alternative is to reserve a /48 for residential customers, but actually assign them just the first /56. If subsequently required, they can then be upgraded to the required prefix size without the need to renumber, or the spare prefixes can be used for new customers if it is not possible to obtain a new allocation from your RIR (which should not happen according to current IPv6 policies).

Can you get static IPv6 addresses assigned? Or do they change periodically?

This might hurt privacy a bit as now each device in the house is uniquely tracked (already possible through other fingerprinting, but with this much moreso).

That's what IPv6 privacy extensions are for. The first RFC specifying that is from 2001 and it has been available in most operating systems for a long time now, although it was buggy for a while in windows.