They did say H-6 may finally be pushed to its limit with these new missiles as they are expected to be so large that H-6 may only be able to carry a single one of these similar to the Beijing Heavy hammer. Hence, they speculate the push for heavy bombers could be that there are so many advanced ALCM/ALBM that cannot be efficiently air launched by H-6 due to their size.
Understood.
In that case, and considering the push for heavy bombers in the PLAAF as mentioned - If these new missiles are expected to grow so big and so heavy such that the H-6K/J/Ns are unable to carry more than one of them per plane using the underwing pylons, and that carrying only one missile underneath the belly of the aircraft:
One or two (parallel) 10+ meter-long IWBs on the H-20 will (not would) become unavoidable, in this case. This means that the H-20 will have to be considerably longer than the B-2, let alone the B-21. This would also exclude pure flying wing designs with shallower wing sweep angles like the ones found on the B-2 and B-21, otherwise the H-20 would become too massive.
Therefore, the H-20 would be considerably large - Larger than the B-2. Estimated overall dimension could be somewhere around the Tu-22M and B-1B in extended wing configurations (if not wider), whereas the estimated MTOW could be somewhere around the B-1B (~220 tons). High-subsonic-capable only, given the massive combat radius and payload capacity required for the H-20's expected mission set.
Of course, this is only my own interpretation and deduction on the matter, given the limited information available on the H-20 so far.