Basically, there are two states you can leave your world in at the end of your story:
- A return to the status quo established at the beginning
- The establishment of a new status quo
If you opt for No.1 remember that, although your world returns to how it was before, your characters will have changed. They will be braver than they were, more daring. They will have fallen in love, or out of it. Had their heart broken or lost limbs. They may have lost friends along the way, or made new ones. A return to the previous status quo acts as a way to emphasise the changes in your characters.
If you opt for No.2 the new status quo will be a direct result of what has happened through the story. Your kingdom will have a new King or Queen, whether literally or metaphorically. Your world may be in a new ice age, humans may have abandoned the planet, nature taken the world back, everyone may have died. There may be hope for the future, or there may be none.