nobody knows when Apple will release the game. The guesstimate is that it would release it at the same time than iOS 7 because they are taking forever, but that's just a guess.
Now, that has nothing to do with what version Dogfight or any other app supports. I don't compile the game to work with ONLY ios 7. Apple enforces that the minimum version to compile with is ios 4.3 which is the one I use for compilation. So if you have over 4.3, it would work. Anything less, Apple doesn't allow it.