I don't think that'll happen anytime soon. There is no doubt that the Chinese government has put a lot of time and money into developing sport talents in China. But like Wongqks said, there are currently not enough physically developed Chinese tennis talents to knock the Western world from dominating the sport. And it's not like the Americans/Europeans are falling behind as well. China has yet to host an established big-name tournament - another sign of its infancy in the tennis world. And population doesn't mean much as well. Japan has over 125 million people, but most of the country's focus is on baseball and soccer, whereas tennis is pretty much neglected ever since Date left the scene *sigh*.
Money doesn't mean everything. Sure, the Chinese government are pumping a lot into the sport, but whether enough people are interested in putting that money to good use (i.e. a significant proportion love tennis enough).
But I don't think it's the physicality which handicapped Asian players from challenging the West. Chang and Date showed that court mobility and accuracy can very well make up for what they lack in size. I think it's 1) sponsers who are dedicated enough to staying behind the players and support a long career and 2) the asian emphasis on education takes a lot of potential practice time for players in developing their skills. About 99% of Asian players study and play tennis before debuting in the professional tour. Martina Hingis needed to practice an average of 5-6 hours a day on court. I suppose anything less than that won't guarantee a place in the top of the tennis league. After all, those in the business world work around 10 hours or more each day in order to try and move up the ladder, and tennis IS a profession, so it's expected that to be the best, tennis players have to dedicate a lot of practice time to honing their skills. I think that Asian players believe that they can study AND find enough time to practice. One example is Mario Ancic. Although he's not Asian, he's a part-time law student and so far, he's still sitting around the world's top 70 whereas he clearly has the talent to be in the top 20. So it's no surprise that the time he spends on hitting the law books is putting a dent on his tennis.