BG and -A upgrades show that this iphone approach isn't the one taken.They are second tier aircraft so I don't think there is an iterative development program going on for them. They will likely keep what they have until their current fit is deemed too outdated.
The whole force is being updated/supported through its full life cycle.
PLAAF can't afford any other approach in the current climate, USAF/Navair is still much bigger. While the core of USAF isn't exactly up to date, quantity matters.