If some dodgy site gets a visitor from a Comcast netblock they would know that, should they ever de-anonymise the address, the John at the other end has zero plausible deniability to fall back on.
That being said, there’s no excuse for Comcast to at least give you the option of a static /48. I see that they themselves have a /20. That alone is enough for a /48 for each of 268 million customers (8x their current userbase) who would each be able to route 65k broadcast domains (/64 subjects.)
I've got a /60 with multiple VLAN's running without issues.
Comcast's IPv6 behavior varies depending on where you live.
If you wish to keep track, I believe this is where pfSense is working on this:
I won't hold my breath!
It would make a worthy challenge, the struggle would be legendary etc 8)
You just assign a ULA address to an interface and that's it. There is no "struggle."