Most foreign students studying Korean know that while knowledge of Korean language is a must to enter the Korean job market, mere knowledge of Korean will not help them get a job in their countries. If one speaks English, Korean can be a plus to get a job in China or Southeast Asia, but knowledge of Korean alone can only get such students as far as getting low paid translation jobs or jobs as tourist guides in their country, but no high paying jobs.
Therefore most Korean language students have one thing in mind: they want to stay in Korea for as long as they can. After all learning Korean can be a huge investment: 6-8 million won a year plus housing and daily expenses. Foreign students of Korean do not want to invest that much money to go back to their countries and get low-paying jobs.
This is not only true of Chinese and Southeast Asian students. Many Russian, European and North American students invest in learning Korean so that they can get a job in Korea. The problem is will the Korean job market accept them?
So far, entering the Korean job market is very competitive and even Koreans have a tough time getting a decent job. Positions for foreigners are limited, Korean companies will put the priority on Koreans for any job that Koreans can do. Even jobs like translation, where technically foreigners should be hired, Koreans hire locals to perform such tasks. As I mentioned previously, Koreans work with people they can trust and know they feel comfortable with. They would rather choose a Korean who respects the local etiquette but performs poorly at tasks than a foreign who can get the job done but behaves "exotically".
What does this mean for Korea? This means that Korea will have an abundant number of foreigners who are unqualified in their countries who will desperately try to stay in Korea. No matter what visa restrictions the Korean government will impose on them, such students will find ways to come back to Korea and get a job.
Such foreigners are "economic immigrants". They choose to live in Korea not because they like the culture but because they can have higher salaries in Korea than back home. They will make little efforts to adjust to Korean culture.
Technically, the Korean government knows the consequences of such issues: the formation of "ghettos", racial discrimination which can result in riots. Last year, when Korean protesters tried to stop the Olympic torch from traveling around Korea in protest for the treatment of Tibetans in China, and Chinese students, most of them studying Korean, gathered in front of those protesters and violent clashes occurred between Chinese and Korean protesters.
Such clashes may happen frequently once a group of angry qualified foreign workers speaking Korean and holding Korean degrees but facing economic and cultural discrimination will try to make their voices heard.