What I am picturing is something more like having One Big Thing the party needs to do (e.g., slay a Big Bad, discover what is at the bottom of the mine, etc), and, rather than providing the DM with the list of things to do first, the DM is given a map of the surrounding area, with some things filled in, other things only sketched out, some guidelines for filling in blank spots a few hooks, and no real "gate" to the endpoint other than them getting their butts handed to them if they're underleveled or their plan is stupid.