Are you meaning that all the crew died when trying to exit the energy field, or rather they crashed and survived for a few generations but ultimately died out before the Defiant arrived?
If the former, then they'd be actively working to avoid the same fate.
The latter would be an interesting story, piecing together what had happened to the crew and their descendants up until whatever event ultimately killed them all off. It would be quite a nice story looking into the lives of children and grandchildren that might never exist, the struggles they had to overcome and the accomplishments they made, connecting with people that came from them but now are no longer. I think they might've tried some option to split the ship in two (similar to Thomas Riker or Voyager in "Deadlock"), allowing the crew to both return to DS9 as well as build their new community, perhaps trying to leave some kind of message for themselves about the disaster that would befall the colony in the future. It could then be left ambivalent as to whether or not the plan succeeded, or could give a definitive answer one way of the other (known to the audience but not the characters).
