Building an "English-only town"???

I'm not sure how well it would actually work.

S. Korea plans to build English-only town
South Korea plans to set up an island town where students can immerse themselves in English without leaving the Asian country.
The town, where English would be the only language spoken, would include educational facilities from primary schools to college as well as learning centers for short-term students. It would be on Cheju Island, about 50 miles off South Korea's southern coast, which was once housed exiled scholars with dissident political views and is now a popular tourist destination.
While creating an entire town would be expensive, officials believe it would save money in the long run.
"According to the Bank of Korea, Korean students spent over $3.3 billion to study abroad last year. We think that if we create a superior educational and residential environment on Cheju as planned, there will be fewer students going to foreign countries to learn English,'' a spokeswoman for the Ministry of Finance and Economy said.
Some municipal governments have set up English-immersion camps, but they offer only short-term programs. Many are now being closed down.
[United Press International]

The students go abroad to study/learn English, of course, but also for the experience of living in a foreign country. They want to experience another culture, and make friends from those countries. There is no way they could replace or fully re-create the experience.