Despite the ability of terrorists to carry out high-casualty attacks within Iraq, al Qaeda may see their eventual defeat within Iraq and this may explain why bin Laden has ordered Zarqawi to go after the US here at home.
Just as Zarqawi fled Fallujah ahead of the US assault in November, Zarqawi will get the Hell out of Iraq as his minions are hunted down. Being pulled out of a spider hole or shot is for the little people--or dumbasses like Saddam and his boys.
It would be nice to kill Zarqawi inside Iraq but I fear he will bug out first.