I read an article yesterday that suggested a reason for all the noise he’s making about the Mueller investigation just now. It is apparently unlikely that the Mueller investigation will indict the president, as Robert Mueller does not believe that’s something that can be done. Instead some minions will be indicted (Manafort already being on trial) but otherwise eventually a report will come out that may list what bad stuff Trump’s been up to.
At that point, no matter what Trump’s done, it becomes a matter of politics as much as everything else. Trump and Giuliani will have been banging on for months about how the investigation is biased and how Trump’s supposed crimes aren’t actually crimes. If the Republican party reckon enough of their voters are on Trump’s side on this then they’ll not impeach him to avoid losing those votes.
Unfortunately while Trump’s been playing this defensive game for several months, Mueller has had no real ability to reply, as he has to concentrate on performing his investigation and producing his report.