I'm not sure which high-profile expats you're referring to. That's not an area I'm familiar with. I do know about the fates of some westerners who went to North Korea. But don't know much about those who went to China.
Under the heading Notable People[0], there are a fair number, American McGee and Sidney Rittenberg[1] especially jump out at me, the latter for being the first American citizen to join the CCP and for his work with Bill Gates to break into the Chinese market. Yes, that Bill Gates.