There are other vectors for MITM in SSL. For instance:
Using a weak cipher with weak hashing function (think DES with MD2, gasp...)
Using an outdated SSL version (eg SSL 2.0, which for some weird reason some sites support even now).
Using a client or server that does not do 1 or 2, but allow doing so (attacker can cause downgrade attacks and force the parties to use a weaker cipher/SSL algorithm, then cracking from there)
These allow an attacker to perform MITM by cracking the encryption or protocol itself, whilst still remaining transparent to the user or server.