Every party want to retain or gain power. And never say never, the communist party today is not the same communist party 40 years ago, likewise, the CCP 40 years from now will definitely not be the same ones today. There are 80 million registered CCP members, from every class, so expect differing opinions and shifts in focus.
Size is not the only issue, education level, communication, and GDP/capital. I didn't say what worked for Singapore will work for China. It was brought up as a example to demonstrate that one cannot compare Taiwan (and Singapore as well) to China due to the vast difference in terms of size, education, GDP/capital.
Democracy is not guarantee rule of law either. Again, India, which has WORSE corruption record than China.