Since the 70's the US has not invested in any significant airframe improvements not relating to stealth technology. Why? Back in the days of the F-4 phantom just about all the Jet Jockies had realized that you could jack the afterburners to the limit and go up to 1400MPH and pull 9 G turns all day, and any reasonably good missile would still beat you. Airwarfare planners call the sub 10 mile range the "Death Zone" because both fighters will likely not make it out of the engagement should both aircraft survive that long, so long as their technology is on par. I don't care how fast your reactions are, the human is the weak link in the aerospace chain. It is the missile and avionics packages that win the engagements, not the airframe(Lets forget about stealth for the moment). The j-10 is certainly faster and more maneuverable than the F-16, but china still does not have a semiconductor and aerospace industry of sufficient maturity to match the avionics packages that Russia can sell, and Russia's avionics/ECM/Radar packages are not anywhere near as advanced as those available to the west. Remember that the F-16 was produced in 1976. Would the USAF still be planning to keep it in service till 2025 if they seriously thought china's fighters would beat it? All of this is interesting, but you have to remember that it is the entire war-fighting mechanism that will win wars. AWACS, advanced munitions, stealth bombers to hit fighters and AA before conventional fighters go into Indian(red, not India) country. The F-16 and F-15 have a place, and guess what? its not to enter into some type of glorified air arena with the enemy's best aircraft. Comparing basic hardware is no more useful than looking at the most muscled team to win a football match, thats not how it works.