It actually might not be too bad if you think about the way Apple designed the cooling system. I don't know for sure, but it seems like the areas up towards the front were supposed to be cooler equipment and not need as much fan activity to cool them down, while the processors and power supply, which produce more heat, were at the back where the fans would blow out of that sectioned off area, keeping the airflow from the front of the computer to a minimum. I would say a good dusting every few months would keep it in good condition most likely. I guess we'll just have to wait and see.
JW