At the earliest, the Ascendants storyline can be dealt with in 2011. And, of course, this is not a sure thing - not even close.
In my opinion, the Ascendants will most likely be treated in an anthology, one covering the entire 5 year gap that recently appeared in the DS9 relaunch. I say that because at the end of "The Soul Key" they are gathered, they have a leader and they have a target - in other words, they are ready for war. No reason to wait 5+ years to fire the first shot - I guess one could be found by the writers, but it would be rather convoluted.