While high performance jet fighters are very sexy and attract most of the attention of Air Force pers and defense planers (and small boys!) alike, we may be nearing the end of the era of high performance manned aircraft. Consider that it is possible in theory to build aircraft with performance far higher than any human could take advantage of (pilots would not be able to deal with the G forces), and weapons with performance higher still (no possible aircraft would be able to evade the effects unless screened by heavy EW or ducking behind a mountain range), and you see the F-35 will have a very short service life.
What will replace these aircraft?
Aircraft are really high performance artillery pieces, so more UAV's being used as "bomb trucks" is an easy prediction. Controlling them via satellite link might be problematic against an advanced enemy or anyone with access to sophisticated EW or ASAT resources. My prediction in the short term is UAV's will be controlled by some sort of airborn command post (resembling an AWACS). As the skys become more dangerous, the command aircraft will have to become more survivable. think of a two seat "Super Hornet" with the back seat operator running the UAV's and the front seater responsible for defending the airplane.
Beyond that, large transport airframes will become the fighting aircraft of the future. A 747 sized transport can carry the equipment and power supply needed to run a owerful laser or railgun, which gives the aircraft the ability to prosecute targets on the ground, in the air and into Low Earth Orbit. Separate UAV's flying ahead to scout for targets (and provide relay mirrors for airborn laser weapons) will also be part of the mix. In theory, such an aircraft flying in a racetrack over the Indian Ocean would be able to provide fire support to troops in Afghanistan or Somalia, further changing the nature of air support. Remote power supplies to aircraft (beaming power to the airframe) and weapons which can deliver firepower across continental ranges at hypersonic speed (like repurposed ICBM's) are other possibilities.
What is needed for the USAF (and our own Air Force) is to come to grips with these and other potential changes and start plans and programs to develop and field these aircraft now so the various fleets don't rust out and the rest of us who depend on air power get left without out umbrella.