Benioff and Weiss said that George R.R. Martin told them that Shireen is going to be burned as a sacrifice.
Obviously, she hasn't been in the current novels nor in the march on Winterefell, she stayed at Castle Black.
I strongly suspect that she will be burned in the coming White Walker war.
Some ponder if George will *change his mind* about killing Shireen, as he has done about other doomed characters in the past, but I think not - I doubt Benioff and Weiss are lying or that GRRM would change something so big so lightly.
Meanwhile, was it a good idea to shift this from the White Walkers to trapped in a blizzard against the Boltons?
I don't know, I think we just need space to process it - I normally don't mind that much when they just move stuff around a little.
Either way, the condition that needs to be met is "Stannis thinks he has no other choice". In the novels, Stannis's march against Winterfell is proceeding...fairly well. I mean they're freezing and starving and losing horses, but he also has many more Northern Houses that switch to his side, they're at least making physical progress - he thinks he can keep going. Plus Melisandre and Shireen aren't even there.
So fine, move the conditions around so now Stannis thinks he's out of all options.
I don't think he's "ruined" as an adaptation so long as something similar was going to happen eventually.