It would be good to know from a pax who actually did transfer at HKIA what procedures are in place.

Regarding the ban on foreign visitors, it could well be that they gradually lift the restriction before the new deadline, as they did for transit.
But it will probably be via travel bubbles rather than a blanket lifting. They might also relax first for business travel before leisure travel. Hong Kong cannot remain a main financial hub and prohibit incoming travel deemed essential. Zoom has limits. Hong Kong has plenty of problems in non-Covid issues and barring business travel for another three months would be suicidal.