Hmm, I'd best remove that feature then
No, there's no plans to allow Facebook logins. I did briefly look into it but it's not something I'll pursue. Hopefully people don't have to change email addresses that often and if you did, but forgot to update TVF you're unlikely to miss any important emails. Be interested to know if anyone would like the option of logging in with their username or email address though?
One option the new site does have is being alerted to new topic posts through Twitter, as well as email. It requires you to be following @tvforum but that's more down to us only being able to send you a message that way (without filling up our public timeline).