When, not if BARR interferes one way or another with Mueller or outcome...then what?

[The Velveteen Ocelot]

3. The House is now controlled by Democrats. They have subpoena power.

While Congress does not have prosecutorial power, they do have the ability to bring to light whatever crimes might have been committed. Don't forget - the GOP was firmly on Nixon's side until the 1974 hearings, which damn near everybody watched, publicly exposed Nixon's involvement in the coverup, with the result that Nixon's public support collapsed. It was only then - because the people no longer supported him (his poll numbers dropped to about 26%) that enough GOPers in the Senate turned against him to make conviction following impeachment likely enough that he felt compelled to resign. Trump's poll numbers are already only in the high 30s, and according to at least some polls, strong support is a good deal less. If hearings were to expose to the public the the extent of Trump's malfeasance, I think the result could be the same as Watergate. It all seems to be following the same path.