I don't think UCAV's will replace allot of pilots anytime soon. In figthing situations people have the right touch to things. Yes, it is true that the possibility of a pilot getting shot down is more than a UCAV because it can pull more G turns and handle more forces. But when it comes to a decision that must be made, only a human can take control.
If pilots get pulled out of programs, there will still be people flying the aircraft from bases or their homes etc. So the CONCEPT of a pilot will atleast stay with us for another few hundred years. Well, that's only my opinion.