One of my favorite books has always been "Future Shock". Published in 1970 by sociologist and futurist Alan Toffler its main theme was that our society was subject to such rapid technological and social changes that people could hardly keep up (they became 'future shocked').
One of Toffler's prime examples in Future Shock was in the area of pop culture and entertainment. His theory of pop culture and entertainment was that each time a cycle went around it took less time to complete it - sort of like the winding of an inner spring of a clock.
So it has been with the movie business (and the shrinking video window). When I first started in this business a blockbuster could play in theatres for up to 6 months. That shrunk to two months. Then one month. Now it is a couple of weeks at best.
And given the numbers I have seen for Harry Potter 7.2 at last nights midnight shows it sure looks to me as if the cycle is may be shortening further. Prehaps we will see the time when we are down to one show.
If everyone goes to see a picture at midnight on the first night then I can see why the studios are pushing for a thirty day window for VOD.