While visiting the DMZ (Demilitarized Zone) on a group tour from Seoul, my guide indicated that many South Koreans would love to see one country instead of two; although she did imply that the younger generation was not as enthused about the prospect.
My first impression was of skepticism. How could such a successful and advanced nation embrace open borders where the economy and immigration would certainly be problematic? After visiting, I don’t think anything is going to happen anytime soon.
The new train station certainly does reflect optimism though. And the current leadership of both are at least talking.
The highlight of the tour for me was the 3rd infiltration tunnel. It was approximately one mile in length, and about 240 feet underground. Called the tunnel of aggression, it was built by the North, designed for a surprise attack on Seoul. We were only allowed to get to the border of North Korea where we encountered three different blockades.
From above ground at the observation point I did get to see the countryside and of course many signs that warned one not to get any closer. The red flags indicate land mines.
Aging Adventurer 
What an absolutely incredible place to visit, so interesting and completely different to anywhere else. Brilliant.
I signed up to see the Joint Security Area (above ground) but unfortunately all tours to this area were cancelled for political reasons (USA and South Korean war games).