The user will see the same Gmail Auth log in screen they have seen many times before. They only have to remember their gmail password (and any password manager works like it always has on this form).
Most likely if your provider is webmail, then you'll already have an active session... so you won't have to type a password in.
Every new site will, every site under active development will. The ones where two input boxes have been the same off grey colour for three years won't change much agreed. It's just a question of whether the sites that ask for username/password now are numerically the majority of login sites in three years or not?
Primary IdPs host the log in page, not Mozilla...
Say Google implements BrowserID for Gmail.
The user will see the same Gmail Auth log in screen they have seen many times before. They only have to remember their gmail password (and any password manager works like it always has on this form).
Most likely if your provider is webmail, then you'll already have an active session... so you won't have to type a password in.