I understand your point, we had the same idea at the beginning but most of the extensions for afrochina were already taken. Moreover, I think focusing on one city, in this case the one the site originated from, is good at making a core community, for people who can meet etc., but this doesn't mean that visitors from other cities and even countries are prohibited from being active members. Also there are and will be more websites about blacks in China (
www.blacksinchina.com for instance) so it should be ok for afroshanghai to exist under that name and focus on its own niche

.
A similar example is Blacktokyo.com which is the leading website for blacks in Japan.
Finally, off topic, some statistics for Afroshanghai visits in November that may prove useful (top countries of origin of visitors, out of 56 in total):
1-China: 66.76%, of which:
-Shanghai: 56.83%
-Beijing: 23.42%
-Guangdong: 4.58%
2-United States: 18.50%
3-Hong Kong: 2.78%
4-Japan, UK and France: about 1.4% each
7-South Africa: 0.8%