The Betrayal at Calth has had all sorts of rumors from all over, telling us both that the game will be limited and not limited. I have had credible sources and sites (100%) tell me for certain they were told it will be a limited run, and ones telling me that it will not be. Personally I think there is a hunt for leaks going on right now that are spurring this misinformation, as I have been trying to track it down myself.
While I only know what readers and sources tell me, I want to point out what I consider the only reliable bit of information that we can see (no matter who it is from), the order list from Games Workshop. This list is in writing and says the Betrayal at Calth is a core game, and in its first print run.
This was posted here earlier this week
Here it is again.
Personally I am sticking to this bit of information, although future printings might take a while.