As always Steve Coll is worth reading and in this article lays out four situations:
What would be the consequences of a second Islamic Emirate? My scenarios here are intended analytically, as a first-draft straw-man forecast: The Nineties Afghan Civil War on Steroids; Momentum for a Taliban Revolution in Pakistan; Increased Islamist Violence Against India, Increasing the Likelihood of Indo-Pakistani War and Increased Al Qaeda Ambitions Against Britain and the United States.
From:http://www.newyorker.com/online/blog...tml#entry-more

I have scanned previous threads, but cannot readily find one that has looked at futurology.