>>8999041 (lb)

>and no player can increase his own expected payoff by changing his strategy while the other players keep theirs unchanged,

wrt Pelosi/Trump, would this mean POTUS has maneuvered Pelosi into behavior she can't risk changing?

She can only try to change Trump's behavior at this point (e.g. impeachment). If she can't get Trump to change, the game's outcome going forward towards election will be determined by which behavior garners the most public approval; Pelosi's or Trump's.