The camera on the 4 and 4S is pretty good the next one I am betting will be the same as the new iPad, lower prices won't happen but the amount of gbs will probably increase on the iPad before we see more then 64gb on the iPhone. With its 6 we will be able to FaceTime on a data connection on some of the devices but this does not include the 3GS or the 4 even.
Faster processor I think is likely, @bossman the iPhone already has a flash on the camera