I'm married to a Korean and have lived in Korea for a fair amount of time. I'd say for this to work well, Korea would somehow need to change a very deeply ingrained idea that watering down Korea would be the end of Korea. There are many times over the years that have had me in situations I've thought "These people would really rather run the population to zero than make it more welcoming and hospitable for foreigners." I can never get involved in politics here, naturalize
requires a strong proficiency in the Korean language, etc. Then just the inter-personal cultural aspects, it's really a lot to think about changing. This year I came to realize that it's so deeply rooted in many ways, that I think often they don't even know it's there.
I'm not as familiar Korean intellectual trends as I was in Japan, but I think there is enough similarity for a comparison to be informative. In the 1970s-80s, Japan was faced with the anticipation that they would need to accommodate massive immigration in the future to ensure their economic future. There was extensive public debate in the media and the consensus that emerged by the 1990s was against immigration. I suspect Korea will go similarly.
You kid, but I foresee a future where stagnant countries fight over the immigrants from the last few countries that are reproducing. This is not just a problem in Korea.
Blue on the map indicates negative fertility rates. The economic systems we have will be destroyed by not having new entrants to the ponzi for the old to retire on. We will realize that expecting the economic growth forever we are used to without population growth forever is folly.
In New Zealand we encourage immigration: 30% of the population was born overseas (very few refugees).
Personally it feels like we are just delaying demographic problems because those immigrants also become elderly and costly in time.
The main problem is that we have a serious outflow of 20-30 year olds leaving for other countries, so just encouraging more kids is not the answer here. I suspect the outflow is caused because 20-30 year olds can't get ahead financially or buy a house. They often move to Australia to earn more in a warmer clime where housing is more accessible.