Too many of the jihadists think that if Islam ever had a presence in a country, then it's an Islamic land and should be returned to their control. E.g. [link|http://www.bbc.co.uk/religion/religions/islam/history/spain/spain3.shtml|Spain], [link|http://www.bbc.co.uk/religion/religions/islam/history/mughal/index.shtml|India], etc. Most people who live there now would pretty strongly disagree with that view.
I don't think we (Western Democracies) can just withdraw inside our national borders and let the pieces fall where they may. We're too dependent on outside resources, and outside trade, and we learned in earlier wars that it's ultimately very dangerous to us to let violent expansionist ideologies run amok.
It's hard to see this conflict between jihadist Islam and the West ending without a major conflagration, though. If you believe [link|http://www.kunstler.com/mags_diary18.html|Kunstler], it might happen fairly soon. :-(
Cheers,
Scott.
(Who generally tries to be optimistic about the future...)