> (3) Presidents cannot be indicted based on conduct for which they are immune from prosecution. On remand, the District Court must carefully analyze the indictment’s remaining allegations to determine whether they too involve conduct for which a President must be immune from prosecution. And the parties and the District Court must ensure that sufficient allegations support the indictment’s charges without such conduct. Testimony or private records of the President or his advisers probing such conduct may not be admitted as evidence at trial. Pp. 30–32
For example, from my understanding this means that Nixon's tapes could never have been used in any form in a criminal trial regarding Nixon's actions.
In today's political environment I don't see an impeachment ever succeeding unless the opposing party has a super-majority in the US Senate.