Whether Jon Snow dies or not shouldn't be spoiler for book readers. Only the dimmest of readers expect Jon to die. The author of the Pink Letter would be the more interesting spoiler. Is there any info regarding the show doing the Pink Letter angle?
The moment Jon gets stabbed will be a huge shock to show only watchers if done right. How to hide Kit in the off-season shouldn't be of any concern. If people find out he's coming back next season, it's not going to ruin the moment.
Premier spoilers:
I would say that the fact that they appear to be killing off Mance for real puts a huge hole in some of the more popular Pink Letter theories.