I don't think he can even fire Bannon at this point. He's already slathered himself with the stink of failure like he was rolling around in cheap cologne and cat piss, another hot-swap of campaign leaders is going to make him look like a desperate, reactionary loser.
Given that Trump himself has at least 3 cases of Rape or attempted Rape reported, that is small fry, if still disgusting.
Not surprising though, unfortunately.