Possibly. I think that would make a huge impact poltically with the rest of Alpha and Beta Quadrant. The UFP would gain a considerable amount of planets, resources and even ships, something that maybe even the Klingons may not like.
Perhaps that is what tips the scale in the Federation's favor. I always had this feeling that the Dominion War put the Federation past all the other powers for good. From then on, everyone else is playing catch up, and if the UFP takes in the Cardassian Union, well that would just further the gap.
"Don't underestimate the power of technobabble: the Federation can win anything with the sheer force of bullshit"