^ well if that's the case (as i'm not an AKB expert either) then yeah we might not be able to see another election in the anime....unless there is a time skip.
In any case we're not even sure if the AKB0048 elections(and management) are exactly patterned after AKB48. I guess we're pretty much speculating.
I still think though that it will be just a single center-nova for the points I've mentioned. Not that I'm too against a duo as I've stated above, Nagisa & Chieri are both cool after all.