What the H-4 Hercules might have carried

What effect might the H-4 Hercules have had if it had been proven and delivered during the war?

It would most plausibly have moved high-value, low-volume cargo beyond the U-boat threat, with anti-submarine work as another possible role.

A proven and mass-produced H-4 Hercules would not have been a general replacement for maritime shipping. Its clearest role would have been moving valuable, relatively low-volume cargo above the U-boat threat. That cargo could justify the cost and complexity of air transport. Anti-submarine employment remains possible, but it is less certain than the strategic-airlift role.