I like the idea that every potential world could exist, but we only actually know about five:
1 – Fairytale Land (vast and diverse, containing maybe four disparate kingdoms – Regina’s, George’s, Henry Sr’s, and Mulan’s; and also possibly Camelot? Unless Camelot is its own world.)
2 – Wonderland
3 – Neverland
4 – The Land Without Colour
5 – And, of course, our world, the one without magic.