Once the report is complete, it can be leaked if any attempt is made to seize it and whisk it out of sight. And Mueller has got a lot of parallel investigations and indictments going on in other jurisdictions that can be used to corroborate the main probe if an attempt is made to cover it up. Old Stoneface is covering his ass. A lot of copies of the report will be released to lots of people, its hard to believe they will all go along with Trump and try to hide it. And Mueller and his team at DOJ will have every incentive to disseminate it to the press if they are cut off at the knees, they know their careers will be worthless in a Trump administration anyway so they have no reason to keep it under wraps.

Trump thinks he's got fake news problems now, wait til the failing NYT and WAPO and WSJ start running the report on their front pages--and this time, all the footnotes will be affixed so people can fact-check it for themselves.