The Dominion - the Bajor Treaty is just a piece of paper. Odo may not convince all of his people that solids are not all evil.
Klingons - knowing how they think and their value system, any people that fights honourably beside them is a valuable ally. Something drastic would have to happen to undermine the alliance.
Romulans - The Empire is weakened after Romulus is destroyed, but that is just the capital planet, not the entire species' domain. They may even ask the Federation for help, but the Federation must hope and pray that the Romulans never find out about Sisko's deception.
The Borg - the nature of the beast means they'll come back. In what form is the key question.
Cardassians - I don't think they'll change as a species. they lost millions of people in the Dominion War, but they only joined the Dominion when the Klingons kicked their arse (and engineered by the Founders). IMO, it's Cardassians nature to be ruthless, cold and authoritarian. Once they recover, old Cardassia will be back.
Delta Quadrant species - None are a credible threat, bar perhaps the Voth and obviously the Borg. The Kazon had to rely on Seska (somebody who knew of Alpha Quadrant politics) to capture Voyager, and the Hirogen probably only captured Voyager as the Voyager was outnumbered. Intrepid class vessels are not tactical ships, I doubt the Hirogen could stand up to a Galaxy, Sovereign or Defiant class vessel.