The evidence to convict them is probably classified. Tying back phishing attempts is not easy to do.
The problem is that once you wrote up the indictment draft, you had to explain details to the Grand Jury and Judge, and those were likely classified. Mueller-team figured they were safe...this would never go to step two.
An extradition treaty (if it were to occur) opens a vast door. I’m guessing that it’ll say that evidence must be presented to the Russians to accomplish the act of them giving up the twelve guys. The Justice Department will say absolutely ‘no’ to giving the evidence, and then Trump orders them to drop the case. They (Rod) refuse, and then the firing can occur.
The phishing angle to this is a bit strange, because they have absolute names attached. Just how they got to the names stage will be highly classified. But all of this will end once a treaty is signed. I’ll bet someone is hired to work on the treaty in the next ten days.