From this article written by Marcy Wheeler:

Now, it is true that Trump can pardon Manafort (though that probably won’t happen right away). That’s the only sane explanation for Manafort doing what he did, that he is still certain he’ll be pardoned. But many of these charges can still be charged in state court.

Just about the only explanation for Manafort’s actions are that — as I suggested — Trump was happy to have Manafort serve as a mole in Mueller’s investigation.

But Mueller’s team appears to have no doubt that Manafort was lying to them. That means they didn’t really need his testimony, at all. It also means they had no need to keep secrets — they could keep giving Manafort the impression that he was pulling a fast one over the prosecutors, all while reporting misleading information to Trump that he could use to fill out his open book test. Which increases the likelihood that Trump just submitted sworn answers to those questions full of lies.

She's also right about Mueller not needing to release an official report if he can keep speaking through indictments.

Her blog is fascinating. If only I knew some U. Mich. PhDs to tag and ask if she's a local legend.