Once again...he can’t do it no matter the circumstances with no repercussions
Wait and see
What repercussions are you talking about? Do you think there are legal consequences? Lincoln fired a number of generals. HST fired MacArthur. Comey has no legal basis to prevent the President from firing him and naming a permanent replacement.
Legally, he absolutely can force that position, the FBI Director, to be fired, by way of AG or acting AG. Politically, this could lead to impeachment, but only by Congress.
In this case, Comey's firing would only be a small piece in a larger obstruction case, but not solely on its own could it lead to impeachment. Does Mueller have the other necessary pieces? That depends on who controls Congress, so right now, probably not. But that could change at some point, sooner than we'd like unfortunately.
While this plays out, Trump is primarily on the receiving end of things. He needs better control of the DoJ, to help make his case if not put Mueller himself in the crosshairs for past misdeeds. But right now their only mission seems to be keep Trump in check receiving fire as if they work for Mueller, not Trump.