China is not India! the penetration rate of smart phone and computer are much much higher than your imagination! Even in the poorest area, peoples are easy to obtain computer or smart phone. Because of there are many Chinese vendor provide very cheaper smart phone and computer. Entire China are fully covered by Internet and Cell phone signal at least 10 years ago.
From your writing, I guess you are a Chinese living in the cities? Probably quite well off too. I believe you are applying what you see in the cities to rural areas. You are correct in saying computers and smartphone penetration is around 60% in China and I have no doubt mobile internet covers most parts of China too. However, mobile internet is expensive for rural Chinese relative to their annual income.
I did not plug the 30% figure out of thin air. It is not my imagination. Mobile internet subscription is around 800 million early 2014, total population is around 1.3 billion. You have to take expats, one person owning multiple mobile numbers, and rural businesses into account. Actual Chinese individuals, having mobile internet bitcoin ready devices, out of total population should be less than your estimate. My 30% could not be far off.
1. I have been to many regions in China. From poorest village to richest cities, I see what's happening in China instead of imagining what China looks like.
Besides, I have been travelled to US and many other countries many times. I have my own comparison between China and other countries, especially for US.
2. According to China Mobile 2010 financial report, mobile subscriber amount of China Mobile has reached 0.98 billion in 2010. Plus China Telecom and China Unicom, total amount of mobile subscriber has already exceed 1.1 billion in 2010. Moreover, mobile internet feature are default enabled at all mobile phone. and even poor Chinese people are able to use internet mobile service since mobile operators provide many sort of package. Take the famous mobile app "Wechat" as an example, there are more than 500 million subscribers in China.
Besides, mobile internet is NOT mandatory required by BTC transaction, fixed line internet is enough to support BTC.
Again, the biggest obstable to promoting BTC in China is to change Chinese people's mind, rather than the infrastructure and annual income.
3. If you have spare time, I suggest you come to China and feel it. People usually has prejudice on many things and easy to be misleaded by press and TV, traveling is the best way to understand the world.