Well it's either Saul or the Cleaner.
Saul gets killed, Walt and Jesse decide they need bodygaurd.
or
Cleaner gets killed/Gus kills Cleaner for failure
and Gus needs a new right hand man.
I would sadly also vote the Cleaner, which is too bad, since I like him more than Saul. He really did some amazing stuff last season... that no more half measures speech was quite the monologue. And him on the attack was great too.