The Achilles Heel of the system is the growing middle class. At some point it will be strong enough to demand the system be opened and at that point repression will have more costs than benefits. The Party will either have to change or be swept aside. I think China's leaders know the day is coming and they're preparing. They don't want it to come too soon since they're scared of the Soviet model and the subsequent meltdown that occurred. If it was up to them, they'd keep the status quo indefinitely but if it isn't possible, they hope they can engineer a soft landing.
(Denny Crane: "I Don't Want To Socialize With A Pinko Liberal Democrat Commie. Say What You Like About Republicans. We Stick To Our Convictions. Even When We Know We're Dead Wrong.")