A popular theory is that Melisandre will be on hand to save/revive Jon from his little incident at the end of A Dance with Dragons. The idea is that Thoros had been seen to revive Beric and Catelyn so, in also being a priest(ess) of the Lord of Light, Melisandre might have that power too. And Jon Snow's just too interesting to get rid of with the details of his lineage still undiscovered.
However, in the series we've now seen Melisandre ride south with Stannis, unlike the books. So how could she be around to save Jon?
I realise that the books and shows have diverged significantly this series, but so far it's all looked to be cutting corners with some characters and, what seem like minor, story arcs omitted. This could really change things though, or suggest that the theory is bollocks (but that would appear to have wider consequences on what most people think George's plans are).