"More: FBI says Flynn was cooperative and provided truthful answers."
That's it, then. The only possible criminal charges, given that the Logan Act is a non-starter, were if he lied to the FBI. If the FBI says that didn't happen, there's nothing more to the Flynn part of the story.
The felonious leaks, on the other hand -- that I expect we'll hear a bit more about. My guess is that Attorney General Sessions will find reason to take an interest in that matter.