Plain and simple, even though Solid State storage is getting much cheaper, a 4GB Flash drive still goes for about 15 bucks on NewEgg for a decent brand. Where DVD's with 4.7GB are about 50 cents each. Blu-Ray discs are much cheaper in comparison as well. So as awesome as it would be to see cartridges come back, it's unlikely.
Plain and simple. They want to control the information flow and cutting out Google is huge for that. Google loses out on alot of revenue. 35% of China is about 700 million people. Thats alot of money they will lose. The Chinese people will hurt the most though.