It doesn't make as big a difference as people think, but a president who won't leave office and has authoritarian fantasies can still be problematic. They can definitely make things worse during their four years in office with the influence they do have.
However, they're not the ones truly in control. Their agenda will ultimately be set by "a collection of unelected figures who have life-long careers in intelligence agencies." And absolutely, "The system will continue to operate as it always has, regardless of who is chosen to be the temporary spokesperson for the ruling class."