I don't believe that Pence was left out of the 'loop', not for an instant. A shade of cover needs to be provided in order to maintain the Republican stranglehold on the Whitehouse. Should Trump be removed or decide to resign who better to take his place than Pence, the President the Party really wants.
What position would Bannon then hold? How many would be swapped out from the cabinet? Who would remain in their positions as Agency and Department heads? Will the citizens be better represented? I see no major changes unless there is conflict of their Agenda. Not to mention the scandal and the outrage involved in having the entire Republican Executive branch removed from office.
Note that the Republicans are not taking any serious action or having any serious conversation about the; already, multi missteps of this administration, including the Russian influence on the election and in the Whitehouse itself. Make anyone else wonder just whose side the Republicans are on? The Republicans now own the field, the umpires, bases, bats and mitts, but I wouldn't hold my breath waiting for the Democrats to bring their balls into the game.