Oh nothing is off the table. But prosecution failed to meet tenets of discovery when they had ample time to do so. Judges get angry over this. Strzok was canned (from the investigation) last summer, but not announced until hours after Flynn entered guilty plea. Seems more than a mere coincidence....
I’m not sure that we have a clear understanding of why Strzok was removed from the Mueller investigation. There have been a few theories, but I’m guessing that Mueller will claim it has nothing to do with bias that could have affected Flynn’s case. Those guys are crafty- sinister & crafty.