Well, if the mass audience doesn't know what the Dominion War is, by all means let that be a license to discount continuity. The problem with directions like that is that you're not making your story set in a vast continuity important, you're making it out of place and overall forgettable. Nothing gained, nothing earned.
Why not open the film Star Wars style by giving a text explanation on what the Federation and the rest of the galaxy have been up to? Star Trek has done it before.
They came from an unexplored region of the galaxy.
A force known as the dominion has declared war on the Federation.
With the recent Borg attack, the Federation's numbers are thin and their allies scattered.
And if audiences like what they see in the Dominion, they'll have an entire series that focuses on the Dominion.