In software world we know how hard estimation is. And to date I have not met a Project Manager, who would commit to a delivery date a year from today. Well. one can commit, but what about keeping this commitment. Recently Boeing postponed first flight test for its Boeing 787 Dreamliner till early fall. This might not sound bad, but what if originally this aircraft was scheduled to take off in 2007?
Surprisingly, in entertainment industry they know how to give promises and keep commitments (at the very least with release dates). How do they do that? I do not know for sure, but my take is that the "secret sauce" should be in very effective scope management. And, of course, expectations management.
When film is announced not more than title, broad story topic, and, probably, some of cast is told out. More details are given out to feed public's interest, but I bet they never tell us about something that can not be done by release date with high degree of confidence.
There is certainly something to learn from this approach.