There might still be potential for future ultra heavy lift airships for niche transports of things heavier than 20 tons, bulkier than 40x9x9', and destinations lacking in an airport.

I'd say the major problem is that the niche may be too small to amortize construction cost across a big enough fleet. A reduction in global poverty may be able to increase demand to make the niche market big enough to be viable. For now we wait.