How many millions of overseas ROK nationals in the Korean diaspora?

The Korea Herald article about reduced emigration from Korea also addressed another topic: the millions of SoKos who live outside of South Korea. It's a rarely touched upon topic, but it's different enough from the original news item that I thought it deserved its own focus. I'm reprinting the entire section so that no data is lost:

Meanwhile, separate government data showed among 2.87 million South Korean nationals living abroad, up to 2.29 million will be eligible to vote in the parliamentary elections scheduled to be held in 2012. The number represents more than 6 percent of the nation’s 37.8 million eligible voters.

The election law was revised in February last year to grant suffrage Korean residents overseas, including some 1.22 million people with a permanent resident status in countries such as the U.S. and Japan. Under the revision, some of them cast their ballots for the first time in the parliamentary by-elections held on April 9 in 2009.

The measure could wield strong influence in the upcoming elections, especially considering the fact that some of the election results depended on a narrow margin of no more than hundreds of thousands of votes.

Up to 73 percent, or 2.1 million overseas Koreans, are living in the U.S., Japan and China, with more than 1.65 million staying temporarily for work or studying purposes, according to the National Election Commission.

The figures, however, could only be temporary as many people are hesitant to register as living aboard or report acquiring a permanent resident status or citizenship in another country, the election watchdog said.

In 2007 the top court here ruled unconstitutional the law that restricted the voting rights of overseas Koreans, prompting moves to grasp the exact number of Korean nationals living abroad and grant them suffrage. The National Assembly approved of the bill calling for such rights last year.

So that's an estimate of nearly three million ROK nationals living abroad. When I helped out with overseas voter registration in Seoul, we were given estimates of six or seven million US citizens living abroad, a number equal to an average state. Given that the US with twice the number of citizens abroad but has six times South Korea's population, that means a South Korean is nearly three times more likely than an American to live outside his/her country.

For decades, if they were to obtain another country's citizenship, they were often stripped of their ROK nationality. Imagine not being able to get citizenship in the United States, for example, lest you be forced to sell your family land back in Kyŏngsang-namdo. They could also lose many of their rights as ROK nationals if they merely obtained permanent residence status in another country (e.g., a US green card).

But lately, Seoul has been reconsidering and changing a lot of these policies, since such draconian measures encourage shadow citizenship, economically and legally hobble ROK nationals who go back and forth from South Korea to another country of residence, and dampen ethnic Korean participation in the electoral process abroad (often with undesirable effects).

For example, South Korea is trying to find a way for ROK nationals to have dual citizenship in a way that doesn't permit evasion of mandatory military service. Spouses of foreign citizens whose countries require their ROK bride or husband to get a green card (or equivalent) if they wish to visit the US no longer see their rights as ROK nationals automatically eroded.

And of course, green card-type residency for foreign nationals married to South Korean husbands and especially wives are now the norm, while paths to residency and ROK citizenship have been opened up to many others. And the thing which has been the biggest boon for me has been the ability to own real estate despite being a foreign national, which was also designed to allow former ROK citizens to keep their land if they obtain citizenship elsewhere.

All of this adds up to a situation where the large number of ROK nationals can more easily make their status officially known. The actual number could be far higher. And if there were four, five, or even six million ROK citizens living abroad, how many would vote in presidential, provincial, or local elections? Can they become a wild card? (Maybe it's all the more reason to institute a Peruvian-style automatic runoff in elections where no candidate has gotten a real majority instead of allowing them to win with a mere plurality.)