Bannon will claim his war is with the MSM and "globalists," but confined within the narrow echo chamber of Brietbart this will be a civil war inside the Republican Party. The call is going out to primary the congressmen that fail the subservience to Bannon test. Given the degree of courage so far shown by congressional Republicans, many will choose to kneel before Bannon to save their jobs.
Why Bannon Was Fired
The statement that Bannon's departure was a mutual decision made two weeks ago is a common face saving cover story. Bannon was fired Thursday morning following Trump's pro-Nazi presser. This is why Bannon gave his own unhinged interview to American Prospect later than day. Bannon wanted his last official act as a presidential aide to be pissing on his boss.
As to why he was fired, Bannon was probably the primary leak source within the White House and he was certainly the devil sitting on Trump's shoulder encouraging his most self-destructive actions.