It's a commonly held notion that if Elsa were to die, then the eternal winter would end. Is there any direct evidence for this in the movie? I can't find any. After all, as long as Elsa is alive, she might figure out how to undo it. If she dies and the winter persists, then the folk of Arendelle are up the frozen creek.
It is indeed commonly believed and I think it would be true because Elsa is like the “eye of the storm”.
For example, during the whiteout scene in the movie the blizzard happens around Elsa. There is this space around her where it’s a bit calmer. The way we can see this is how Hans gets to Elsa and how he has to go through this sort of snow whirl around Elsa.
Another example are the snowgies. If Elsa does not sneeze then there’s no snowgies.
If there is no source then there would be no consequence. If Elsa weren’t there to be the “eye of the storm” then there’s no storm.