I have a slightly different theory which has no scientific merit, but is based on my own experience.
My theory is that the "top" part of the beer clears the most quickly. Since you are constantly pulling beer off the bottom, you are always getting the cloudiest. Assuming the keg is unmoved for the entire time, your last pint is that top, clear, gorgeous pour.
I have come up with this theory because of kegs that sat weeks in the keg (at serving temp), and then were drank within a week, and still the last glass was noticeably more clear than the previous several. I would hypothesize that, given enough time, you would be able to get the entire keg that clear. My beer rarely lasts more than 12 weeks after brewday, though.