The question made me think. I think South Korea has been working towards that scenario for the longest time. It has fairly good relations with China today, both economic and diplomatic, while North Korea is increasingly more isolated. Removal of US bases will make China much more open to the idea of Korean unification, as they will not have to worry about keeping a buffer to maintain distance from US forces.
South Korea Armed forces:
Republic of Korea Armed Forces - Wikipedia, the free encyclopedia
"Manpower
Military age Mandatory 18 to 35 years of age for male, wartime conscription 18–45 years of age
Conscription 21–24 months depending on the branch
Available for
military service 12,483,677 (2005 est.), age 15–49
Reaching military
age annually 344,943 (2005 est.)
Active personnel 639,000 (2012)
[1] (
ranked 6th)
Reserve personnel 2,900,000 (2012)
[1] (ranked 3rd)
Deployed personnel
12 nations, 1,156 troops total
List of major deployment
[2]
Expenditures
Budget
₩ 33.0 trillion (2012)($30 Billion USD) excluding
₩1.68 trillion($1 Billion USD) given by Korea to
United States Forces Korea[3]
Percent of GDP2.52%
The South Korean armed forces were largely
constabulary forces until the outbreak of the
Korean War. It was heavily damaged by
North Korean and
Chinese attacks and in the beginning relied almost entirely on American support for weapons, ammunition and technology. During South Korea's period of rapid growth, the military expanded accordingly, benefiting from several government-sponsored technology transfer projects and indigenous defense capability initiatives.
Modernization efforts for the ROK military have been in place since the 1980s. The GlobalSecurity.org website states that "in 1990 South Korean industries provided about 70 percent of the weapons, ammunition, communications and other types of equipment, vehicles, clothing, and other supplies needed by the military."
Today, the South Korean armed forces enjoy a good mix of avant-garde as well as older
conventional weapons. South Korea has one of the highest defense budgets in the world,
ranking 12th globally in 2011, with a budget of more than $30 billion
U.S. dollars. Its capabilities include many sophisticated American and European weapon systems, complemented by a growing and increasingly more advanced indigenous defense manufacturing sector. For example, by taking advantage of the strong local shipbuilding industry, the ROK Navy has embarked on a rigorous modernization plan with ambitions to become a
blue-water navy by 2020.
[4] South Korea has a joint military partnership with the United States, termed the ROK-U.S. Alliance,
[5] as outlined by the
Mutual Defense Treaty signed after the Korean War. During the outbreak of the
Vietnam War, ROK Army and the ROK Marines were among those fighting alongside South Vietnam and the United States. More recently, South Korea also takes part in regional as well as pan-Pacific national military wargames and exercises such as
RIMPAC and
RSOI. Among other components of the armed forces is the
Defence Security Command, originally the Army Counter-Intelligence Corps, which had a major role in monitoring the military's loyalty during the period of military rule in South Korea."
Korean People's Army:
Korean People's Army - Wikipedia, the free encyclopedia
"Manpower
Conscription17 years of age
Available for
military service6,515,279 males, age 17-49 (2010),
6,418,693 females, age 17-49 (2010)
Fit for
military service4,836,567 males, age 17-49 (2010),
5,230,137 females, age 17-49 (2010)
Reaching military
age annually207,737 males (2010),
204,553 females (2010)
Active personnel1,106,000 (2010) (
ranked 5th)
[1]
Reserve personnel8,200,000 (2010) (ranked 1st)
Expenditures
Budget~$10 billion
[2][3][4]
Percent of GDP~25.0%"
We can also compare their GDP figures:
South v North Korea: how do the two countries compare? Visualised | World news | theguardian.com
Life In North Korea Vs. South Korea - Business Insider
My opinion, the US should keep the Mutual Defense Treaty and US-ROK alliance status, but should make an orderly and phased withdrawal of bases from the Korean peninsula, to facilitate the unification on a realistic pace.
The bigger question is even after Korean unification, if that were to happen, what would be Unified Korea's threat perception from immediate neighbor, China, who by that time (lets say 20-30 years from now) will probably become militarily the most powerful nation on earth and technologically at par with the US/West. To address this concern, Unified Korea should keep the option open for return of US bases and to reduce dependence on the US, pursue a policy of building alliance with other nations who would be open to such ideas and who are uniquely complimentary for mutual needs. These nations I believe will include:
Japan, ASEAN, Muslim world (Sunni)
(I kept out India, because I believe large nations like India and China do not have need for equal partner or allies, but are more interested in client or tributary states relationship)
Note here that today some Chinese South East Asians are trying to divide ASEAN unity (perhaps with a goal to make parts of ASEAN into China's tributary states), and its possible that they have their hand on an effective and explosive issue that is the biggest obstacle to ASEAN integration, but I will address that OT issue in another thread. One cannot sweep these kind of issues under the rug, so they should be explored and analyzed in detail for future geopolitical consequences.