Well for me, on the 5th Gen.
If they don't have an V8 option, that will be my biggest request. There is no way I'll sell my V8 for a V6.
Other things I hope they fix is the HVAC system, it's totally worthless in my 04. In the winter time, it's either blowing out heat so hot (even with it set to 65) or freezing cold (at lo) that I'm always messing with it, hoping to get it to stabilize at one temp. Then it always fogging up in the winter time, any time it rains it starts fogging up. You turn the defroster on, it goes away but within seconds of turning it back to another vent, truck fogs up. Doesn't matter where the recirc is set either.
If my old beater car can have a slider control where I set, and never touch it the rest of the trip. My brand new truck with all the fancy electronics should have the same advantage.
Other then that, I just hope the next gen still has some toughness and doesn't become another grocery store SUV.