When my husband was about 9 and his younger sister about six, his father moved their family to a town near Stuttgart, Germany, for his job with the Army and Airforce Exchange Service. They lived "on the economy," meaning in a regular neighborhood rather than on a military base, and the children were enrolled in German public schools.
Though challenged at first, they both learned quickly, and within months were participating in school and playing with neighborhood kids. We have relied on his experience to encourage us that our daughter will have a similar ability to learn English upon arriving home. And indeed, volumes of anecdotal evidence tells us that this will be the case. But what of her Chinese speaking, reading and writing skills?
When my husband's family returned to the U.S. five years later, both children were fluent in both English and German; obviously, their parents had been able to keep their English skills intact during their time abroad. But anecdotal evidence and limited research studies have indicated that Chinses adoptees who are immersed in English-only environments start losing their first language within weeks of leaving China. Further complicating the situation is the fact that leaving behind the Chinese language seems to be a major coping strategy for some of these kids--so tinkering with the language attrition/acquisition process may have significant emotional consequences, as well.