{snip}And every one of these is accomplished in Dungeon World's mechanics/process.
Sorry to snip, trying to keep it limited to what I'm directly responding to (but genuinely thank you for explaining DW further).So, in these kinds of narrative games, generally speaking, there may be things which happen where the explanation is consequences of PC actions in the past, as simple 'living world, stuff happens', or even as someone gunning directly for the PCs (and this could simply be introduced by the GM, not necessarily a consequence of anything). The focus is always on how these situations relate to the premises and goals of play.
Since I don't actively prep more than about a session's worth of material at a time--about what I expect the PCs to encounter in a session--I keep track of a lot of ideas in my head that are sorta pending. (Though there was one situation where I kept track of time while the PCs were out of town, so I'd know how long ago things had happened when they got back--this is not my usual approach.) From what I read of AW (which I realize isn't exactly DW, and which I bounced off of pretty hard so my understanding might be skewed) it's a more-formalized version of my approach to things; it really didn't seem likely to generate different stories than the D&D games I run (setting settings aside), and your description of how the ideas I floated could be brought into a DW game doesn't change that impression.