Nicholas Carr's post on 'the sixth force' (extending Porter's five-force model) came to mind reading this story on the dying ritual of moviegoing form the LA Times.
Apart from the obvious reasons (internet and games, home cinema and DVD, high ticket prices and gas prices), Patrick Goldstein mentions how "it's become cool to dismiss movies as awful" and that "bad buzz about a movie hits the streets fast enough to stop suckers from lining up to see a new stinker".
However, Hollywood has not yet succumbed to this pressure. "The creative voltage is sometimes so low that you wonder if you've wandered into an insurance office." And: they should "start releasing any movie with multi-generational appeal on DVD the same time it hits theaters, so kids could get out of the house and the parents could watch at home".
This relates to Mark Cuban's plans for simultaneous releases (theater, DVD, pay-TV), with movies from director Steven Soderbergh. That could actually be a paradigm-shift of sorts and Hollywood's road to the 21st century.