I gotta say the GPS is unlikely. The problem is that Apple has been getting the GPS antenna/chipset as a bundle deal in the 3G/4G cell chips, not in the Wi-Fi only board. To include GPS that means there has to have been a shift in that part chain which I haven't seen any news on by anyone. As much as I'd like to see true satellite based GPS show up in the Wi-Fi only versions of Apple products, I just can't believe its going to happen.
Likewise the "gamepad" cross-device compatibility just seems unlikely. If Apple wanted to throw in some generic drivers for bluetooth gamepads in the "typical" (2 joystick, 1-pad, 4 shoulder, 8 button) configuration they could easily overtake Nintendo as major handheld gaming system, in the course of a week.
I've used JoyPad over Wi-Fi and it kinda works, but it still comes down to the lack of physical button holds things back. The tactile really is important if you don't want to have to look at the controller from time to time.
What I will believe is some kind of greater remote control functionality. For example letting an iPad or iPod "type" to a Mac or control mouse movement. VNC/RDP/ARD are very popular control methods in the iTunes store, and it's something Apple really could/should have from the start.
I'm still waiting for them to be able to let an iOS device act as screen/input device for a headless MacMini or similar "home server" box.