As kids, Cassian and his sister would figure out how to get off that stupid planet without waiting for a Deus Ex Evil Auntie From Harry Potter.
Then, they’d meet some space wizards.
There would be a big bad, possibly the chick who plays Ilsa, She Wolf of the Empire SS. They’d kick her ass in a massive final battle with more space wizards and laser swords. And in the end, the space wizards would space wizard with all the space wizards.
Because this is Star Wars, not Blade Runner. The End.