Unmanned combat air vehicles.

As part of my final yr project, My group is designing an unmanned air vehicle, with the performance parameters slightly tougher than Global hawk.
Visiting this website has made me think about unmanned combat aircraft. I just wanna ask people, if they think that there is a good future for it and exactly what role they can/may have. Further more, could UCAV’s ever replace an entire air force i.e no pilots at all ?
What projects in this regard are there going on at the moment ?

will look forward to hear from all…

Regards.