I would think that to be a sufficient hole in your thought process. But good theory.
I wouldn't call this so much a hole as an unexplained part of the book; I'm not making a comprehensive explanation, just theorizing on one facet of this world. I suspect that the mist killing has to do more with Ruin and TLR's death, rather than changes coming from the Well's power and TLR's death. (While the failure to come up with a good explanation for the mist's behavior is an issue, I would call my theory more "incomplete" than "flawed") (I'm hoping someone else will be able to take this and run with it)
Edit: If I'm right about another Well, we should call it the Well of Descension.
You, actually, can't say that your theory is merely incomplete due to the unanswered questions left for book three. You could however claim that it is a complete meritable theory based on the existing evidence, which makes it as valid as any other thoery based on what we know.
It could very well be flawed, but given that we are only hypothizing, in a sense, it is a complete speculation that, due to its insufficient information, is unable to fully answer some questions.
If you were to recieve that information, then it no longer be
your
theory but everyones ( Or, err, the truth of the books) reality...
However, you will be credited for it, that is a different matter. It is the same as Newton and his thoery of gravity, he did not have the suffecient amount of technological advancement to proove what he suspected--or convince the scholarly world--but when Einstien made these theories
official
, though they are still Newtons theories--the concept of gravity became everyone's truth.