Here’s the reality. Trump had no problem whatsoever firing Rex Tillerson. Trump has no problem firing those that aren’t doing his bidding or are no longer useful to him. Trump hasn’t fired Jeff Sessions. Logically, then, one could easily conclude that Jeff Sessions is doing Trump’s bidding and/or Trump still deems him useful.
It remains to be seen whether Mueller will open an obstruction investigation into Trump’s firing of Tillerson. Mueller is already investigating Trump for firing Comey and for ***thinking*** about firing Mueller.
Trump can’t fire Sessions, Rosenstein would be in charge and he can’t fire him either, and even if he could, the Senate would hold up the nomination process for a new AG!