Recently on the military channel they've been featuring what is called "active defense" systems. Which are defense systems that engage threats rather than waiting to be engaged like traditional armor and other "passive defense" systems.
To me, this seems like it might be very much viable for USAF aircraft. One of the primary threats our planes face are missiles. we already have technology that can train a laser beam on a missile from the ground and destroy it. If we could mount a similar system on aircraft it would in theory offer superb protection against both air-to-air and surface-to-air missiles. In the modern era of stealth technology this might not be a big improvement on current systems, but in the event that new radar systems defeat stealth this could be a viable alternative.