All the Disney Princesses that got their films remade have been made queen: Cinderella, Aurora, Jasmine (Sultan). But why hasn't Belle been made queen?
Belle was never a queen in the original films, was a peasant and as far as we know, never married Beast, and would unlikely be accepted as the queen of France, as Beast was not the King of France, but simply the prince.
The Queen was very much alive still in the movie. Until she perishes, and Beast and Belle marry, she will not become Queen.