3 to 10 years now, the speed posture isn't going to change, and unless you are in an active state of war, no one will really try to shoot you down either. The best they can do is intercept you and escort you out of their space. Unless you got aircraft that will supercruise (don't know if the F-35 itself can do that), it still won't be easy to catch one of these aircraft down low, and supercruising also eat up that much fuel. Unfortunately it does not turn out that turbofans are more efficient than turbojets in supersonic speeds. At some point, it is the turbojet that is *more efficient* at supersonic speeds.
At _supersonic speeds_, the same aircraft with the same TWR, one using a turbofan and another using a turbojet, the turbojet would use less fuel. The engine has a higher exit speed for the gases, which means it can attain the same thrust for a lower volume of air passing through the engine. Hence why fighter turbofans are low bypass.
The faster you go, the better that the bypass gets lower and lower (at the expense of fuel efficiency in subsonic speeds), till bypass becomes effectively zero, and with that, you get a turbojet. Turbofans use a fan stage to bypass some air over the engine core and into the exhaust. So long as the air bypassing the engine is much faster than the plane speed, this works relatively well. But as the plane speeds go faster and faster, this scheme begins to work less and less effectively, as the difference of the speed of the exhaust gases vs. the plane speed narrows. This is why as speeds go higher, its better to have more thrust through the engine rather than the bypass, finally reaching the point its better to have all of them.
In addition, at these speeds, the relative simplicity of the turbojets works to its advantage. The turbofan still has to drive that large fan, and that extra friction and rotating mass to deal with, so the turbofan incurs more parasitic losses. As turbofans need to work at much higher compression ratios, there is also greater risk of breaking down in supersonic flight.
Back in the sixties, jets with fairly low TWR with turbojets, were hitting Mach 2 to 2.5. Today you have to brute force a high TWR on a plane with turbofans to get up to those peak speeds.
The Flanker carries its own bag of problems as a recon plane. Things used to enhance maneuverbility, flaps, leading edge slats, LERXs, compound geometry on the wing edge, a longer wing span and a higher wing aspect, all add up to significant drag at supersonic speeds. Whereas the J-8II uses the classic sharp sweep delta wing with a hard forward edge. On a straight line, the J-8II should have less drag than a Flanker (but then so will a Starfighter or Mirage III).
Add the fact that our recce plane will be flying clean, while the intercepting plane would be flying with tanks and missiles, and you got the recipe for a clean run away.
The JH-7A isn't going to be any better than the J-8II for this role. Actually far worst. High plane weight, low TWR, turbofans, fixed inlets, compound geometry wings meant more for maneuverbility---variable camber slats, sawtooth edge, etc,. The latter stuff adds drag.
These principles wont change 5, 10, 15, 50 years from now. Maybe the plane will change, but not the concept---UCAV with sharp arrow-delta shaped wings with solid edges, powered by turbojets or ramjets, screaming over the airspace with a catch-me-if-you can flight path.
