why North Korea will not change?

It will not in fact ever change with out an outside intervention or a majot internal collaps. The people ahev been long since disarmed and have no recourse but to live under the thumb of the totalitarian rule of the current ruler. It is unlikely any nation will be altering that any time soon and it is equally unlikely the people of N Korea will depose him either. This is what happens when you completely disarm a society.