Since beating Cain, Werdum has gotten knocked out after running face-first towards his opponent and then decisioned a guy in less impressive fashion than his first decision win against the same opponent.
Meanwhile since Cain lost in that debacle at 18,000 feet, he has destroyed a guy in one round, that guy being the same guy Werdum couldn't finish two different times.
Cain beats Werdum 999,999 times out of a million. I doubt Werdum will ever be elite enough to earn a fight with Cain again (as Cain will win his belt back in his next bout), but should they fight, Cain will send Fabricio into early retirement, guaranteed.
Cain is the HW GOAT and that honestly can't even be disputed