Right, but eventually you have to lock it in, or there would be no point in announcing a release date or letting your customers know when to expect it. While I

Right, but eventually you have to lock it in, or there would be no point in announcing a release date or letting your customers know when to expect it. While I like the idea of never worrying about any kind of completion date, I would think it's better for business to set customer expectations. Of course it backfires if you don't hit that date, but not having one could also backfire if when the project is done no one cares to use it anymore. For me it starts with predicting accurately units of work, regardless of desired completion date. Then work with that to speed things up if needed, and use that information for estimation.