One country (DPRK) does not make a rule. An besides, the DPRK and the Islamic Republic of Iran are very different regimes with very different citizenry. Iranians, by and large, do not believe in a death cult of personality surrounding their leaders, and can be much more critical of governmental choices.

Cuba? Burma? Syria?

Iraq, for that matter. They suffered under severe sanctions and a no-fly zone that left part of the country beyond the control of the state for over a decade and Saddam was nowhere near being overthrown until the US and allies actually invaded (again).

>Cuba

OK, maybe beginning to see a pattern

>Burma

I'm not an expert on Burma, but haven't they become a democracy again? I'd like to know what/any effect US sanctions had on this.

>Syria

I don't think this is a great example against isolation causing regime change

The North Korean government is being propped up by China. If China withdrew support their government would collapse.