Correct me if I am wrong but isn't this guilty plea exactly for the instance Sally Yates warned the WH about? And if so, this was the reason given as to why Trump fired Flynn, that he lied to Pence.
If this is the same than it's Flynn admitting he lied about the Kislyak meeting he took AFTER the election where he told Russia to not worry about the new sanctions. This is big news because was Flynn going rogue and meeting with Kislyak on his own volition or was he acting as a Trump surrogate and carrying a message from Trump? And if he was acting as an official surrogate at behest of Trump than he had ZERO reason to lie to Pence about this meeting. Flynn lied to the FBI about it - was he ordered to do so by Trump/Pence? Also Pence claimed on television interview that Flynn never met with Kislyak nor discussed sanctions - and when Yates memo leaked Pence was caught with his dick hanging out and either Flynn lied to him or he lied to American people. Trump then fired Flynn to protect Pence by claiming Flynn lied to Pence. BUT if Flynn was acting on behalf of Trump Transition Team when he met with Kislyak it means Pence knew all along, as did Trump. Which means Pence knowingly lied, which will go to obstruction of justice for making false public statements.
Mueller has a shitload of charges for which he could have had Flynn plead guilty to - that fact that he chose this one is telling. He's sending a message to Trump again.