Assuming it's true: The PS3 can't sustain another Uncharted game because they just want to whore multiplayer. Other than the water effects, UC3 did nothing we hadn't already seen in UC2, they just couldn't be bothered putting as much effort into story, character development, back story, hell even offline bonuses.
I'm sure Naughty Dog could easily create a game that would surpass UC2 or 3. The biggest complaint about UC3 graphics I've heard is they can't keep character faces looking proper. Fix that, then complain about the PS3.