With Gates, Manafort , Flynn, Cohen, etc. all ready and willing to sing the question is will the Mueller team be able to get them all to sing in harmony putting together a long trail of indelible evidence that will sink Trump? That's not an easy task.
Here's an outcome worthy of thought. GOP loses control of at least the House. The evidence of high crimes and misdemeanors is iron clad but getting articles of impeachment through Congress will run up against the 2020 presidential election.
In response the Republican caucus goes to the Democratic caucus and says, " hey blue here's the deal. In exchange for not moving to impeach we get Trump to agree not to run again What happen to him after he leaves office is a matter for DOJ to figure out".