Not likely. Kim Jong Il's brother-in-law was generally understood/guessed to be the one holding the reins of power in 2008 when Kim was ill then and will likely take firmer control again, even if its from behind the scenes, using Kim Jong Un as a figurehead for perhaps a decade. This is similar to what happened when Kim took over in 1994 after his father's death.
There isn't sufficient command & control capability or maneuverability for the NK military to take swift control of the country or perhaps even the capital, if the party apparatus (cadre, spies, police, informants) doesn't stand in its way.
I purposely chose "power play" over "coup d'etat" to allow for less sweeping changes. There will certainly be a push by the military for a greater share of power.
Looking at the released list of funeral mourners, this has already begun. A few surprises in the order, though it could be a ruse. Everything in NK is a ruse, tough to ever know anything for certain, even with 'educated' speculation. But its fun to try (if you are outside of NK). :-)
