If the Borg hadn't have been absorbed/defeated in Lost Souls and David Mack (and others) had led the Borgs invasion of the Alpha/Beta Quadrant to it's most logical outcome. I suspect they wouldn't have stopped. They may very well have given time, destroyed the entire Federation, it's allies, it's enemies and then for good measure, spread out further and annihilated everything in this part of the Milky Way.
Maybe a handful of ships would get out, but as the collective was hell bent on destroying all of Humanity and the Federation. They would have pursuded them and would more than likely destroy everything they touched.