First of all, it means that he'll be getting some significant playing this summer as opposed to some half-paced friendlies. Remember, he flashed in some friendlies last year, only to not quite look the completed article in the Premier League. In fairness, he did come on strongly towards the end though.
However it's also of great interest that we see South Korea do well at the tournament. Like every other Korean male, Ji must serve a minimum of 21 months in the military prior to his 30th birthday. Currently that's some way off, but he could be made exempt from such service due to a rule which states it they finish in a medal-winning position at the Olympic Games, they will be spared.
The Koreans look to have one of the easier groups at the tournament, containing themselves, Mexico, Gabon and Switzerland.
With Ji at a crucial stage in his development, he's unlikely to be doing any national service yet and taking a break from the game before he's even established in it, but should he go on to be successful in the next few years, it would be beneficial that he either sticks around here, or should he not, there's little hindering his potential sell-on.
Still, as far as the more immediate future, the very best of luck to Ji this summer. We'll be rooting for him, and reporting on him (and any other Sunderland player at the games) in this site!