IMO, it'll be a nasty mess if the balloon goes up with DRPK vs. ROK/U.S.
My gut tells me their huge army and artillery assets will make the opening of such a conflict insanely bloody. Casualties (American alone) will probably be far greater than Afghanistan and Iraq in the first day. Seoul will be a burning mess. Nasty surprises like sapper tunnels will be common.
However, in the long-run, I think the "paper tiger" effect that pre-collapse USSR and Iraq had, born of the DRPK's poverty will begin to play out, primitive command, communications & control, and logistics/mobility issues too. The tactical and strategic inflexibility that the militaries of paranoid authoritarian regimes tend to have will lead entire divisions into killing zones of modern ROK and U.S. weapons.
We would win, and it'll be a damned mess, but not as bad as some would think.
But yeah, DRPK and Kim Jong have a vested interest in the status-quo as is. This is still a long shot. A DRPK provocation escalating beyond control is more likely than them going into full-scale war with premeditation IMO.