The Kryptonite Theory by LOST Latvian

IF LOST is in fact rooted in parallel realities (all Fringe-like) and characters jumping to another reality receive a certain immunity from death, a neat theory that has been speculated here by other LOST lovers, then how does this relate to the loophole?

Well, perhaps Jacob is from another reality and is effectively immortal just as Ben and Widmore may be (remember their conversation in Widmore's bedroom).

IF so, then PERHAPS only someone from the same reality as Jacob can kill Jacob.

And IF Ben has been switched from one reality to another as a child after getting shot by Sayid, then PERHAPS he's the embodiment of the loophole and is capable of taking out Jacob.

Possible Implications:

1) MIB deliberately hardened Sayid against Ben and facilitated the near-death shooting. This would be very diabolical, dark, and show consistent.

2) This could explain why Jacob never met with Ben in person, knowing that he's essentially his Kryptonite.

3) Widmore himself may have been switched, and if so may also be Kryptonite to Jacob and/or MIB. -- Perhaps he figured out how to switch realities after Ben played him and he called Ben out, "I know WHAT you are boy." -- Maybe Ben is effectively immortal as well. Knowing that, Widomore may have been forced to counter by switching.

Anyway, the root of the theory is that only people/agents from your reality/world/dimension/time can kill you and influence your reality. Perhaps the mythology of LOST is based on such a causal rule set.

Whaddayathink? Know of any similar theories or posts I should look at?