My initial reaction is no Bannon, no reelection.
The only way for Trump to save this is to double down on his agenda, ie build the wall, cut legal immigration, get us out of pointless ME wars, stop china trade cheating, etc. Since Bannon's ouster would seem to indicate the ascendancy of people like McMasters and Gary Cohn who oppose Trump's agenda, that seems unlikely.
If true, this move would fully confirm that Trump is now officially just a figurehead president and actual power lies in the cabal of ex gen's he foolishly appointed. He will have decided that his only hope of retaining office is to align with one part of Deep State. He chose military wing rather than legal/bureaucrat wing.
Bannon's reaction will be crucial. If he takes to breitbart and goes on attack against Trump, it's all over.