Trump isn’t going to fire him. the probe is going to collapse from embarrassment and try slip away like a silent fart. The stench will remain.
And to extend it with a grade school analogy - he who smelled it, dealt it.
Trump is most certainly acquainted with N. Bonaparts advice, “never interrupt your enemy while he is making a mistake.”
I suspect that the coup plotters have been neatly maneuvered into position.