What happens depends on which “royal household” you mean, but in a monarchy the throne doesn’t usually become vacant permanently just because the household leaves. If the king is still alive, the household can simply be dissolved or replaced; if there is no king and the royal line is gone, succession rules or Parliament would determine what happens next.

In practice

  • If the royal staff or household members leave, the monarchy can still function through the sovereign, ministers, and court officials.
  • If there is no eligible heir, the country would typically follow its succession laws or constitutional procedures to name the next monarch.
  • In the British case, people discussing this scenario note that Parliament could also choose to abolish the monarchy and move to a republic.

What this means

For most monarchies, the system is designed to survive personnel changes, even extreme ones. The bigger issue is not the household leaving, but whether there is a lawful successor and whether the state wants to keep the monarchy at all.

Simple version

  • Household leaves, king remains: the palace still functions, just with different staff.
  • No king and no clear heir: succession law or Parliament decides.
  • No monarchy by choice: the country can transition to another system, depending on its constitution.

TL;DR: The royal household leaving does not automatically end a monarchy; the real question is succession and constitutional authority.