There are two main reasons I doubt we’re going to get any smoking gun proof of secret coordination between Russia and Trump’s campaign. The first is simply that, even if it had happened, there’s no reason to expect that unambiguous evidence of it would necessarily be available to the FBI. Collusion, after all, is ultimately a question of the conversations people had—and in this case you’d expect that at least on the Russian side there would be an acute understanding of the need to keep those conversations secret. If those conversations were conducted in person, there’s no real way to retroactively prove what was said unless one of the participants confess. If they were telephone conversations, the same applies unless one of the parties happened to be under electronic surveillance at the time (and using an actively monitored communications facility). Absent that, you might be able to show a suspicious volume of contacts, but on the critical question of what was said, you’d be out of luck. Conspiracy is just inherently a hard thing to prove unless one of the conspirators flips or is dim enough to leave a paper trail.
That’s actually secondary, however. The primary reason I doubt we’re going to see that smoking gun is that it’s hard to see why it would be in Russia’s interest to loop the Trump campaign in on their interference campaign. The risks would be significant, and the benefits hard to discern. As Lawfare observed last month, there is ample evidence of collusion and coordination between the Trump campaign and Russia—it’s just that all of it took place right out in the open. Russia’s efforts on Trump’s behalf were, for the most part, pretty open, even if Trump affected not to notice them. Trump’s praise of Vladimir Putin—grounded in an affection that long predates his political career—was public, as was his gleeful exploitation of the fruits of hacks against his opponents and encouragement of more of the same, as was his attempt to exculpate Russia long after the intelligence community had reached consensus about their responsibility, as was his use on the campaign trail of stories pushed out by Russian state media. Trump could see they were helping him, they could see he appreciated it and was reciprocating. What, exactly, would have been the marginal benefit of some further secret communication making this happy symbiosis a matter of explicit agreement? Collusion would have been redundant.
One benefit might be apprising the Trump campaign about what to expect, or inquiring as to what forms of assistance would be most useful. But none of that requires the kind of explicit confirmation of a state‐sponsored information operation that people have in mind when they talk about “knowing collusion.” All of that could be accomplished via cutouts that preserve plausible deniability. So, for instance, Trump confidant Roger Stone appeared to have advance knowledge of forthcoming Wikileaks dumps of hacked Democratic e‐mails, and acknowledged communications with both Julian Assange and the “Guccifer 2.0” hacker persona, now widely regarded as a front for Russian intelligence. If Russia wanted information from the campaign, or to privately convey information to the campaign, they clearly had a plethora of channels to do it without anyone concerned having to say out loud: “Vladimir Putin is trying to influence the presidential election, and here’s how we can coordinate our efforts.”