I think that a lot of people who work on deadlines like this have learned how to incorporate this into their products overall structure. Think of games that have to be released on a proper timeline for a specific holiday season. Now instead of trying to meet those deadlines, game developers are putting out a minimum product and releasing updates, patches, and missing portions of the game in chunks after the official purchase/release date. Whether this is successful or not is up for question, but it seems to be one strategy for coping with amorphous deadlines.