My only reason for thinking that Mueller will blink and not make a “finding” that Trump obstructed justice will be because at that point any and all evidence that may have influenced the president's actions MUST be made public, including all “classified” evidence. You can't allege a president committed a crime and then claim that ANY of the evidence is classified. And Trump would, of course, mount a vigorous defense of his actions. And there would of course be congressional hearings, all in public. This would rip the heart out of the deep state, and ultimately, it would implicate 0bama in a bevy of criminal acts.
Knowing what we know now, I suspect Mueller's pals in the deep state are pleading with him not to make any allegations against Trump, and to let the matter go. If he presses forward they know they will all be exposed.
There are no rules or standards for any of those people. If there were, we wouldn't have had FISA warrants from a fake dossier or a special council.
They make up the rules as they go along. And with a nonexistent AG, we are stuck in hell.