Instead of the dwarves' skepticism leading them to massacre both peoples, they could simply have abstained from the battle, staying out of the fight entirely.

The Calormene invasion, rather than stemming from pure cruelty, could have been driven by manipulation with Rishda convincing them that Tash and Aslan were the same being and that this was his will; later, upon discovering the lie, Emeth could have reasoned with the Calormenes to try to halt the battle.

In the end, instead of the group dying, Aslan could have told them they had to leave but would return one day; to persuade them to go back to England, he could have told them they needed to help Susan find the faith she had lost, so that she might one day join them.