I think the DOJ is just using a simple organized crime strategy against the Trump team. The DOJ knows that people in the Trump campaign were communicating with the Russian government. There was strong evidence of something illegal going on, which is why warrants were granted to conduct surveillance. And they have evidence of a coverup, because they went after the attorney general shortly after he took office. If this was all just about recordings of some legitimate diplomatic calls this would already be over. If this actually implicated Trump or Bannon or Putin it would be over. But it’s not over.
That means that the FBI knows what was going on. They know who did it, they know when they did it, they know where they did it. They could bust these guys right now and file charges. But the DOJ doesn’t have evidence to convict whomever was in charge. The DOJ might not even know who was calling the shots. So they’re setting up a net around all these guys and tightening it. The Trump guys thought it was OK because their guy Jeff Sessions was going to be able to shut all this down from the inside, but now he’s recused himself because he knows that he’s just setting himself up for more prison time if he doesn’t. So now everybody is scared. Flynn is scared. Manafort is scared. Sessions is scared. Donald Trump Jr. is scared. Their staff are scared. Paranoia is going to set it. Soon each of these guys will have his own lawyer telling him to cut a deal. Staffers will have their parents hiring lawyers. And the leaks will keep coming, because the DOJ wants these guys to know that they have no secrets.
Eventually one of those guys is going to start talking to the DOJ. Then they’ll all start talking to the DOJ. And eventually the DOJ is going to have a case against the guy at the top. Even if Trump isn’t the bad guy he’ll have no credibility left. He’ll either resign in disgrace or live out out the most pathetic one-term presidency since Buchanan.