How long will Shogun Rua be out for?

Unbeknownst to him, Shogun Rua suffered a torn ACL in his left knee during his victory over Lyoto Machida.  So far, he has had three surgeries on that knee, and doctors are not sure if he will need another.  Given the amount of recovery time he will need, it is very likely that he will not fight again until sometime in 2011.  Will the UFC need to issue another interim belt, this time for the Light Heavyweight division?  If so, will anyone serious compete against Lyoto Machida for an interim title?