The next generation Radar and Ladar developers have a brief of finding the F22, plus the next generation of stealth. Thoughts.
Stealth is definitely the way forward, and there are quite a number of nations developing stealthy programs (ranging from quite advanced stealth-UCAV programs in countries that range from the US, France and South Africa, to stealthy airplanes in nations ranging from Russian/Indian Pak-Fa and China's JXX, to lesser known stuff like the Iranian Shafagh concept, the Singaporean geltonas-lamoc MAV-1 and the Saudi financed AES SAT 800 Falco). Hence it appears that stealth is definitely here to stay, and several decades from now there is a good chance that virtually all nations that really spend on defense (meaning nations that have a good aspect of their GDP tied to military procurement ....thus nations ranging from Brazil to Britain) will have their airforces having at least 'some' level of stealth. Goodness, there is even a stealthy jet trainer by Germany's DASA called the Mako that has been purchased by the United Arab Emirates and is being marketed to several other countries.
Anyways, all of the above is not a threat to the United States. The nations that are truly capable of coming with 'real' threats to our air supremacy (not just superiority but supremacy) will not be against us (i.e Western Europe will not be our enemy). As for the nations that will tend to be anti-US, for example Iran, what they field in the air will not be a real threat. For example the Iranian Shafagh, IF it ever becomes more than a mock-up model, will simply not be a threat to anything the US has. Hence most of the 'foe' nations will not field anything that would really threaten US air supremacy. The only nation that might be a problem is China, which is the only nation that may have foe status and would be a threat (I personally believe that Russia will be on our side, as will India, due to the rise of China and thus I do not include them here).
Hence when it comes to aircraft there is no real threat to the US ....apart from a future China.
The real threat is in the form of future generations of missiles, especially of the cruise and anti-shipping variety. They will be smarter, faster, stealthier, and more lethal. And events in the past, such as the whole Falklands thing where the Argentinians sunk 2 British warships (and damaged a third), as well as the case in 1987 when an Iraqi exocet missile killed 28 Americans when it struck the USS Stark, have shown that it is possible to hit the US. Now, an exocet attack would be folly when matched against our AEGIS system, and even more lethal missiles like the Yakhont are no guarantee to their users(although they are still very lethal). Hence a nation like China is definitely thinking hard about being able to reach out and touch American naval superiority, and it is FAR cheaper (though still expensive) to come up with a truly effective stealthy missile than it would be to basically match the US ship-for-ship. Think of it as a rich-country's assymetrical warfare, where a lot of money is spent on getting something that while expensive is still a whole lot cheaper than matching the other country.
The other thing is obviously detection of stealthy aircraft, and a nation like China must be working hard on this. After all, with the fall of the Soviet Union the only nation left that would really require the use of all of Uncle Sam's toys is China. Take the B2 for example ....while we used it in Afghanistan, it was basically swatting a fly with a billion dollar golden hammer! While the Spirit is capable of bombing the cr@p out of Afghani targets, that is not what is was meant for. It was meant to attack truly hot targets deep inside the Soviet Union, and with the fall of the USSR China is the only nation that would really warrant its use. Hence the Chinese must know that if anything ever went down they would be facing all the top-of-the-line toys Uncle Sam has to offer, and they would be facing them hard. Thus they must be working on ways to increase the distance that a stealthy B2 (or F22 for that matter) can come without detection. Whether they will be able to do that though is another question ....especially when it comes to their efficacy levels. By this I mean that while it is possible for them to increase their chances of picking up (say) the Spirit, it still remains that the Spirit will have already done its job. By the time they can pick it up, even with augmented detection systems, it will be literally too late. There are rumors (probably true) that the Chinese have some of the wreckage from the F-117 stealth 'fighter' that was shot down in Yugoslavia, and that older long-wave radars can pick it up, but there is a world of difference between the Spirit and the NightHawk. I really doubt the Chinese would be able to stop a Spirit attack ....at the very least not until it was too late and the B2s had already taken out their targets.
Anyways, I think it will be pretty interesting to see what happens in the next 50 years. The US will obviously continue to be the premier (by a good margin) superior force on sea and in air, and obviously Western Europe will continue to have very very very good systems (eg radar systems like PAAMS, and missile systems like the upcoming Meteor and SCALP). However there will be new players, such as the Russian/Indian combo (where Russia, flush with oil revenues and thus able to get back to real development, plus needing a country -like India- to act as a buffer against a rising China; and India, with its frenetic economy and need to be able to stand up against China....Pakistan is honestly not a threat to India, apart from the nuclear perspective). And then, of course, there is China. China, by the way, will probably make quite a good number of nations rise up. For example the Japanese are taking no chances, and will soon have so called 'helicopter destroyers' (actually JSF-capable aircraft carriers, but the pacifist constitution doesn't allow 'carriers' hence 'helicopter destroyers'), and Australia's HUGE radar system that can basically see anything coming from the direction of China. This radar is already operational by the way, and its capabilities are quite amazing. Thus China will make quite a number of nations change, and I personally wouldn't be surprised by a nuclear capable Japan (goodness, I'd bet a friday beer that Japan could come up with nuclear weapons within months ...if not less....if it needed to).
Anyways, let me stop my rambling and go to sleep. Take care and God bless. BTW ....all of the above is my 2-cents, thus to any FReeper finding any errors in it mea culpa. It is quite late and there is a good chance there are several inaccuracies. Actually I'm almost certain.