I do not think a regime change stands a chance. What is happening in Afghanistan, for example, is not going to bring them 21st century. A country infested with Islamists seems to top out some where pre-industrial revolution. Unfortunately we are pumping 100's of billions of dollars of oil money into Islamist Theocracies.
You have Saudi Arabia financing schools all over the area that take children who have not attained the age of reason and teaching them that not only is it OK to kill jews, americans and infidels in general, but it is a DESIRED activity to be highly praised. That is the problem. No regime change to people who have been brain washed this way is going to change that.
The mind has been stunted before it reaches the age of reason. Would you enter into a negotiation with Saddam Hussien or Yaser Arafat? Islam and the Koran make hero's out of making deals with infadels when the islamic faction is weak and then going back on you word once you become stronger.
Populations ruled by Islamists are taught to react, and not to think or question. They are trained to be so xenophobic that their duty is to kill anyone that thinks or reacts differently. You do not reason with a mind that has been debilitated in that fashion. You use enough force that they feel their own and their families survival threatened. Hopefully they start thinking before you have to use so much force that they end up dead. If not, then oh well.
Using cookie cutters or nukes on a few select cities would start some people thinking. Some of them would think they better attack the USA harder. Those would have to be given more force. It would only be counter productive if you stopped doing before the job was done.
An Islamist Theocracy is mutually exclusive with civilization. We either have to remove them or build a very big wall around them. If we attempt to tolerate their thought process by treating them as though they are civilized, it will be the end of civilization as we know. Might as well start studying the Koran right now.
Like the intact Cherokee, Maumee, Potowatami, Naragansett and Seminole regimes we left behind a hundred years ago?
Sometimes genocide is a policy tool. Sometimes it works (USA vs. AmerInds, Turks vs. Armenians, Spanish vs. Arawaks). Sometimes it doesn't (Germans vs. Jews, Hutus vs. Tutsi's, Serbs vs. Albanians, Serbs vs. Bosnian Muslims). Genocide is and should always be the last resort. That said, if this Islam vs. USA crap can't be resolved any other way and it comes down to "this planet ain't big enough for the both of us", I'm for us, not them.
The problem with nukes is that the fallout is not so easy to contain. Biological warefare is much "cleaner."