Going on the idea that it is Melisandre who resurrects Jon, using the same sort of magic we've seen from Thoros of Myr to bring back Beric Dondarrion, exactly how would Jon react to that? After all, this is a woman who has murdered numerous people, even poor Shireen, in the name of R'hllor, and the likelihood is she'll need to murder someone else in order to bring Jon Snow back. Someone dying so he can live isn't something I can picture Jon being all that happy with. Melisandre may think that she's doing the right thing by resurrecting him, and that she can turn him to the Lord of Light. In reality, she may just be signing her own death warrant.