President Trump is quoted in this Politico piece as saying he won't fill a number of vacancies in executive agencies because the agencies are too big and the positions are not needed.
Regardless of what this does for the efficiency of the Trump administration, IMHO it's bad news for future Republican presidents. Why? Because typically the top-level positions in an administration, those at or just below the secretary level, are usually filled by people who have gained experience by serving in lower level positions in the preceding administration of the same party. That's the way the Washington swamp operates. Clinton had problems because it had been 12 years since the last Dem administration, so he didn't have a wide range of experienced potential appointees.
Of course, at this stage we aren't worrying about the next Republican administration, but still.