I would like to offer a (somewhat preachy) perspective that I hope raises some questions.
Having any kind of social identity based on religion or national cultures is a terrible idea. The idea of preserving a particular culture is also terrible, it should be CULTURE AS SUCH that is defended against erasure therof. You know community, poetry, music, art, debate, thought, food etc.
Jews should be defined as anyone who energetically practices or wrestles with certain rituals, customs, languages etc., or feels a strong and brave tie to them. And such people wod not only be Jews.
Chinese should be be the same.
If you can speak Chinese fluently and are tied deeply to it, you are culturally Chinese. If you were born in Jinhong to a Dai family, but study hebrew, celebrate Passover etc., you are just as Jewish, if not more, than say Bob Dylan or a million other "genetic" jews.
And none of these things should be your social identity, or your group that you are loyal to, anymore than being a jogger, surfer, sci fi addict, painter, or chef is. Now rinse and repeat forever. Your social identity might be something like "human being" "global citizen" or some similiar concept.
There used to be Jews in China but they were assimlated due to lack of anti-semitism. They lost their culture, because it wasn't their's anymore-and they gained another one, more suited to where they had moved too.
So no loss at all, actually.
The idea of a jewish diaspora still happening now is ridicluous or at least anti-human, as is the idea of a Jewish state. Follow this logic to it's conclusion.
It is 2011, genetic/racial identity, public religious identity, cultural homelands etc. should have seen their day by now.