Nice theory. It will be interesting to see if it is true, and what bungie does with this. For example, after Halo: Reach, maybe they will finally tie the two stories together, and then go back and make more in the Marathon series, or even remakes of the originals.
We will see what happens, but it will be a while before we know.
Again, nice theory, it was a well thought out idea, and a joy to read it.