You've got your facts a little bit wrong. While the Borg cube featured in "Before Dishonor" was in the AQ before "Endgame", the Borg fleet in "Destiny" attacks because of the events of "Endgame".
That being said, it's also said in "Racing the Clock" (may have the title wrong) that in pretty much every timeline where the events of "Endgame" didn't occur, meaning the Caeliar don't run into the Borg at the space and time when they do, the Borg essentially end up overrunning the Milky Way.
Hell, in RtC Temporal Investigations is ready to bring Janeway up on charges shortly after Voyager
's return, but some reliable sources tell them, essentially, that there's no point.
In short, there's no easy answer.