Interesting theory.
A lot of it does make sense and while it's pretty clear that the kernel of the idea was always there in the show, some of the choices, plotlines, characters and macguffins that were introduced (and some were summarily killed or dismissed) it's clear that they didn't really much of an idea of how to get there. A lot of that can be blamed on the nature of television programming but I think the writers are as deserving of some of the blame.
Still, despite my qualms, Lost was a very important series and one that was mostly enjoyable to experience as it played out. I need to do another watch of it sometime soon, but with both DS9 and Farscape on my plate right now, I'm not going to throw another television show into the mix. Plus, I'm extremely leery of both Seasons 2 and 3. I have a lot of bad memories from those seasons.