This may have already been discussed, but the QUESTION that led to the SPOILER about Jack not being there to deliver the baby, is interesting. Here is the question (from the E transcript)
Q:Are Walt and Claire's baby yin and yang, good and evil, Ernie and Bert?
A:That is an interesting theory, my friend! I can only tell you this: When the big castmember dies off, Claire's baby is born--and Jack is not the one to deliver it.
From the face of it, that question has NOTHING to do with Jack not being there to deliver the baby, does it? When you have the question there for context, what does it mean? (Am I making sense???) Hmmm, maybe Walt is the one to betray somebody, thereby making him the "evil" to Claire's baby's good. Otherwise, it makes no sense. And I'll say it again, Kristin is VERY reliable. You know, it still doesn't make much sense, because anyone looking at that is going to think, oh, Jack is dead then. I GIVE UP!!