It is easy to have a knee jerk reaction right after a traumatic event but to answer your question, If we enter a cinematic dark age, it will have zero to do with this shooting and will be pushed by the continuing expansion of the 'Michael Bay' effect.
I think it will be a bit of both. They will look at what Nolan's creative vision supposedly led to and may figure that a Dark Knight/Dark Knight Rises is worth truly less than Michael Bay films.
But there will also be another reason which will enable the cinematic dark age: China. China now has the second highest amount of ticket sales in the world. And please note this is of last year, when only 20 foreign films were permitted for theatrical release. Now, with last year being such a big success, they are now allowing for 34 films to be released each year. This has changed plots completely, from Battleship to Red Dawn. Film producers are now consciously thinking about the Chinese audience when they make these films. You know what China doesn't allow to be released in this country: R-Rated films. So regardless of this recent tragedy, there are going to be less R-Rated films regardless due to China's overwhelming presence (and I still have yet to see Prometheus because of this).
So with China on the rise, this tragedy causing a national media and public shite storm, and the popcorn eating masses continuing to prove they'll pay for stupid bull shite (though for the most part I've been proud of film goers this year for what they're paying big money to see), the timing is perfect to frick everything up and make it a producer driven industry that plays it safe rather than creative driven industry like most writers and directors want it.
This post was edited on 7/21 at 10:15 pm