If the President of the United States dies in office or is impeached, the Vice President directly ascends to the presidency.
If this Vice President also dies in office or is impeached, then who becomes President? Does this Vice President, upon taking office as President, also need to appoint a new Vice President?
Trump is already 79 years old, and his death in office is a very likely event. If Trump dies, Vice President Pence would directly become President, but if Pence is impeached, who would become President?