But you have to place North Korea and South Korea in the proper global context. Neither are especially prime actors in that sense, but they are allies of greater powers. You also have to factor in the impact of nuclear armement on global tensions. Then there's the economic and energy interests of the likes of Russia, South America (Brazil, Venezuela), India, Middle-East (Iran, Saudi Arabia) and of course China. Korea could be a prelude or a catalyst.
No it cant, because of nuclear weapons.
Nuclear weapons are (strangely enough) the reason for the relative peace between the great powers in the later 20th century.
See, the US cant go to war with Russia, or China. Pakistan cant go to war with India. And Russia cant go to war with France or China.
Why? Because of the threat of nuclear annihilation, the greatest incentive of all against war! There might be proxy wars and espionage from one country against another, but there cannot be open warfare.
That is why it's impossible for the Korean conflict to go global like WW1 did.