What are your ideas for that happened in the time between DS9 and the 32nd century? If the Dominion kept expanding at it's rapid pace seen on DS9 it is possibly that the Dominion already borders the UFP though the Dominion advanced technologically slower in DS9 then the UFP showing pronounced conservatism and changing tech only when the need arises, the UFP probably is technologically superior to the 32nd century Dominion. (Even with tech plundered by the Dominion)