Only two U.S. presidents have been empeached and a third resigned before empeachment.  Neither of the empeached presidents were convicted of the crimes they were accused of.

Impeachment does not necessarily result in removal from office; it is only a legal statement of charges, parallel to an indictment in criminal law.

Both of the empeached presidents, Andrew Johnson and Bill Clinton were acquitted by the senate and so stayed in office to end of their terms.

Nixon

Richard Nixon is the most interesting case.  He decided to resign before the impeachment hearing, thus avoiding both empeachment and being turfed from office.

Following his resignation, Vice-president Johnson (Nixon’s running mate and friend) pardoned him.  This avoided a trial where he was actually convicted and sentenced.

The acceptance of the pardon is said to represent an admission of guilt on Nixon’s part, but that is just supposition.  If he had declined the pardon and gone to criminal trial many would have been more satisfied.

Trump

Recent events involving former FBI director Comey and Trump have raised the possibility of obstruction of justice, which is a crime.  High crimes and misdemeanors can be a cause for empeachment.

If empeached though, the senate would still need to vote Trump out of office by two thirds majority which based on past history, is unpresidented ( no pun intended).

Whether there are tapes or not of Trumps alleged obstruction, it is highly unlikely he would resign like Richard Nixon.   So to all you hopeful optimists out there, I don’t think its going to happen.