Well, let me put it this way: I can say, without fear of contradiction, that Shireen is not going to be burned by Stannis before the Battle of Ice, leading to his defeat by the Boltons.
How do I know this? Because in the books, Shireen is 700 miles away from Winterfell and Stannis is less than three days ride away. Moreover, Stannis’ army is running out of food and couldn’t make the trek back to the Wall.
So, while Stannis might yet burn Shireen in the book, the context for the decision will be entirely different. And context matters far more than the mere event itself. After all, it’s not a spoiler to say that the salesman dies at the end of Death of a Salesman. What would make it a spoiler is to explain how and why that event actually happens.
And increasingly, I don’t think the show is going to give us the right context. Myrcella probably is going to die – Maggy’s prophecy, after all – but I doubt it’s going to be due to Ellaria Sand giving her a poisoned kiss so that she can die in Jaime’s arms.