We'll see shortly, but I think Manafort will cooperate

Based on the new Information filed by Mueller, it contains one count of conspiracy to obstruct justice and one count of witness tampering. https://talkingpointsmemo.com/muckraker/manafort-reaches-plea-deal-with-special-counsel-mueller

If Mueller is willing to let him off the hook with only 2 counts there has to be cooperation. There is absolutely no reason why Mueller's office would go that easy on him without cooperation.