i think the main problem with this concept, and with BWB aircraft, is the difficulty of resizing them, to vary passenger capacity. with a conventional airliner, if you want to add seats, it's a fairly simple matter to stretch the fuselage, likewise to reduce capacity, it's not to difficult to shrink the plane.
i think it would be much harder to to this with a BWB, the whole fuselage would need re-shaping.
just my two bobsworth.
I think it's little difficult to design non circular cross section pressurized cabin without weight increase. This fuselage must have pillar or wall in the cabin to keep pressure tight strength and skin thickness is larger than cylindrical fuselage. Elevator is located tail of the fuselage to reduse drag same as JAXA's SST.