It's quite interesting what can be done with autonomous aircraft. At Linköping University, where I study, there is at least one project going on that deals with autonomous aircraft. As my field is artificial intelligence, I've been in contact with this project a couple of time, although I haven't been involved in it directly. But the results are very impressive.

Of course, what I've seen is for civilian (traffic control, for instance) use, and not a replacement for military fighter aircraft, so it might not be entirely relevant here.