Eclipsa with little Meteora on her arms.

Notes:

I'm calling it right now, Eclipsa and Meteora will try to claim the throne through legal means.

And they will do this after Star manages to make Mewman and monster co-exist.

And because Eclipsa and Meteora are the rightful heirs because they were born first, they get the throne.
Kicking Moon, Star and mewman out of the kingdom thanks to the legal power that Star gave to the monsters.