Hmm, so you think DayZ is going to end up on Arma 3 instead? Or both?
Probably both. But I doubt it will ever come out of the beta stage whilst using the ARMA 2 OA engine. The engine is too inherently buggy, so it'll be near impossible for them to fix all the bugs in DayZ. It'll come close but not before ARMA 3 imo.