Not sure why you believe that. Thus far this Kim has done nothing that wasn't done before and his predecessors were not ushered out of there. I think what you say could happen if he goes too far but thus far he hasn't made that move yet.
Up to now “Containment” worked...despite the frustrations. But things have changed for China and S. Korea.....both economy's growing...not to mention technology isn't going to let the people there stay in the dark as before...they are realizing the lie they have lived under the Kim's. Therefore it would be better that China and the S. Koreans work at replacing Kim....then to wait until the people actually rise up and flood all the borders.
Some have said there's enough N.Koreans in the know now to make such a transition...but it still needs to be done on the “hush” while things are set in place.
Who really knows how things will work out...but the “Global World” is not going to want to deal with any rogue type nations....as we have seen occurring these past few years. One by one the leaders are being brought down. I think possible it's now Kim's turn...maybe not..but we'll see in time.