Bannon was openly contemptuous of Trump; if Trump didn't know it (and apparently he didn't), he was the only one who didn't -- until Bannon called Robert Kuttner to express his contempt for Trump. For Bannon, Trump was a Useful Idiot, until he wasn't useful any more (hence the Kuttner interview); for Trump, Bannon was his guarantor to the racist, Nazi, KKK, white supremacist base that Trump would remain faithful to them.  Trump has secured that base; they know he is one of them and Trump no longer needs Bannon to be his ambassador to them. 
Bannon in Trump's face (from Breitbart) is not significantly different from Bannon in Trump's ear (in the White House). From either perch, Bannon pulls Trump's strings, and one way or the other, Trump continues to dance to Bannon's antisemitic, racist tune. Despicable.