I do agree with you that a normal subsonic flying wing design wouldn't take *this* long to cook especially when H-20 project should be started in the same approximate time period as all the other "20" projects. Now we are legit seeing J-20 replacement flying all over Chengdu and other advanced derivatives J-20 surface in recent years but still no progress from the H-20 project. However it could be possible that China lacks the experience with large aircrafts thus contributing to the long development time but even this is a bit too long for that reason. If H-20 do indeed turn out to be a supercruising design, IMO it will almost certainly need the efficiency gains of next gen ACE engines to remain competitive range wise without being absolutely humongous. Perhaps it being delayed this long is due to waiting for suitable engines to be built. It is IMO possible that the updated design for H-20 could resemble Lockheed's LRS-A proposal:
View attachment 150975
Supposedly a basic wind tunnel model of it posted on SPF
Basically a large VLO supercruising bomber but as we all know this design was not chosen probably due to cost and feasibility concerns but with modern tech like highly efficient ACE engines and more composites allowing lighter airframes it could potentially become more feasible.
But all this is basically my speculation on why the project took so long and with redesigns what it could potentially be so take it with a large spoon of salt.
So it's very possible and likely that H-20 do indeed turn out to be a normal bog standard subsonic flying, but IMO something like this isn't 100 percent impossible especially with the amount of rumored redesigns and "putting it back into the oven" the project has gone through.
