The reason that Flynn is getting off for zip jail time before the case is presented is because he is probably the star witness in the congressional hearings that will likely come sometime in early 2019.
I say his star witness status is critical because, he's free and clear and if the Judge and prosecutors finalize the deal ... he can recount if t hat is the truth. When Flynn tells his story he won't be under the thumb of the government. You can bet that he'll be playing up his military background including the humiliation he's felt.
I'm probably wrong but I suspect the unrelated criminal investigation cited in the Flynn filing was a crime that Flynn was aware of that that he believed would not be prosecuted. That belief had contributed to his adoption of cynical Trumpian values - get it any way you can.
I think the conservatives have to know, because of the 2/3 vote of the Senate, Trump could not be convicted making impeachment a tactical dead-end without significant Republican support.
While I have I have kept up with this story, I've not obsessed to the point of charting the players. I just know this is a complex web of acts and actions that involve a whole lot of folks. I fully expect to be surprised by revelations that may be in directions no one thinks about now.
It promises to be an interesting story, wherever it goes.
Cohen is also on the stage for the state as it rolls out the story but Flynn's feat of being taken completely off the hook - putting his crimes right - adds to his credibility because he could theoretically flip back to trump.