Without the wormhole, it's hard to see the Dominion as threat, if they take a fleet of ships here on a 70 year journey they still have no backup and no allies and no supplies...
That would be a 70-year journey based upon the known technology of the time. Science progresses constantly, technology advances. Pre-Wright Brothers and flight, a trip from Toronto to mainland China would have been a long, dangerous, expensive trip over water and land. But less than 10 year later, all of that changed.
FTL travel could be improved and allow the Dominion to get to the AQ a lot faster than 70 years. Also, don't forget gateway technology since there was a partially-functioning gateway found in the DQ, there could have been others. And the ability of the Caretaker's species (sorry I do not know the name) to transport ships over vast distances.
The Dominion would have come to the AQ eventually and they would have attempted to conquer the AQ. With or without the wormhole's existence.