So, this is obviously a pretty significant development. If Mueller’s office is right that Manafort lied in the course of his supposed cooperation, it suggests a couple things... assets.documentcloud.org/documents/5280…
(1) Presumably the cooperation sought from Manafort concerned other people’s conduct, in which case any lies would be aimed at protecting those other people. Which would be an awfully big risk to take unless you hope it will be rewarded with a pardon.
(2) Mueller’s people are confident enough they can PROVE he’s lying about some material fact to accuse him of crimes in a court filing. Which would imply they’ve independently got the goods to that effect.
(3) Manafort belived he could get away with lying. Suggesting either an assumption that a pardon was coming soon, an expectation that the special counsel would be sacked soon, or a radically inaccurate assessment of what Mueller’s office already knew.
(4) Trumpworld can draw all these same inferences, which is likely to increase pressure on Whitaker to do the task he was appointed for relatively soon.
(5) “Hurry up and sentence me, then” is a response that reads to me as a forcing move from a party confident that his stall tactic has served its purpose. 
Obviously all of this is speculative & based on a thin layer of public information. But Manafort, whose personal track record doesn’t really scream “martyr for principle,” is playing chicken with spending the last couple decades of his life in prison.
Which could, I suppose, be a symptom of congenital arrogance, but to me implies high confidence—perhaps ill-founded—of an impending extrication by skyhook.
Of course, Trump is not famous for reciprocating the loyalty he demands, so he may well opt to let Manafort twist in the breeze now that he’s torpedoed his own credibility as a cooperator.
Which way that goes probably depends on whether Manafort can offer anything independently verifiable if he realizes the cavalry isn’t coming.
