Yes, a whitewash is a possibility.
But, I wouldn’t say that Comey being fired for “insubordination” is a bad thing in and of itself. If I told my boss he wasn’t under investigation, and he said, “Please announce the current state of the investigation”, and I refused... out the door.
Comey did that (and much more), and it was certainly enough to let him go. And, even though Trump doesn’t have to justify the firing of someone who serves at his pleasure, it weakens the contention that Trump fired Comey to proetect himself, i.e., obstruction of justice.
But, we at FR know he did far more. The question is, did those things make it into the report.
“But, we at FR know he did far more. The question is, did those things make it into the report.”
First thing that comes to mind is usurping the authority of the DoJ.
Second, political espionage.