This is never ever going to happen and you will probably get banned again with this kind of tech fantasism. China is not going to use the H-20 to drop gravity bombs on the CONUS. Even if such a bomber was feasible it would be so expensive that a tiny amount would get built, which is obviously crippling on every other mission type.
Supersonic speed is not realistic for the H-20 because it has a low use for it. Air to air capabilities would exist, like the B-21, but these will be very secondary and will primarily be for self-defense. AEW functionality or a CIC will not exist. These require structural features that are detrimental to the aircraft's primary mission set.
Entire point is that what's the point of a H-20 when you have a GJ-X drones? The latter are likely much cheaper and deliver better payload for cost.
You're going from 2 engines to 4 engines, and now making it manned in a 6th generation environment where drones, CCAs, and UASF are de rigeur, and if all you get for the increased cost and a manned requirement is large hypersonic carry, it's sort of a waste.
On the other hand, if you want AEW&C / EW roles, supersonic speed helps A LOT, because it allows you to move with the fighter / drone fleet, and also allows you to flee when you lose.
The entire point is, we've seen that the J-50 and J-36 have mastered tailless agility, so a H-20 shouldn't need folding tails. What are the tails for, then? Yaw stability in supersonic dash.
Moreover, even for the pure hypersonic carry role, the supersonic speed helps a lot because if you lose stealth (and the Americans are working on counter stealth satellites), you still reduce time on target and inject V initial into the hypersonic.
I'm not saying that supercruise would be a requirement, and I doubt supercruise would be worth the cost, but supersonic dash, to reposition, to egress, etc would be important just for the hypersonic launch mission. Once you have supersonic dash, things like theater command, operations command, all of these become cheaper capabilities.
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What this ultimately comes down to, is the H-20 a 5th / 5.5th generation aircraft or a 6th generation aircraft? If it's 5th-5.5th, yeah, subsonic. B-2 clone with B-21-comparsble avionics. If it's sixth generation, when unmanned platforms dominate, it's probably going to be capable of supersonic dash, if only to add initial energy to its hypersonic payload.