As someone who uses an email address that no longer exists to log into Facebook, I'm not sure what you're implying about the inexorability of email addresses. May I ask for an elaboration?
If I may jump in here, I believe lugg was suggesting that email addresses are much more longer-lived than another type of username you might use to log into a service.
Reasonable! I've just been through my fair share of primary email addresses over the years (be it from my ISP, university, or the webmail provider du jour), so the idea of an email address being forever unchanging was a bit incongruent with my experiences. :)
As usual the solution is to add a layer of indirection by getting your own domain name and then you can swap out backend email services without changing your address.
