Helicopter airlines are notoriously difficult to sustain (economically).
Regular (or even scheduled) shuttle flights over short distances have proven more resilient and of which Heli Air Monaco is perhaps the foremost example having been operating continuously since 1976.
In 1990 East Asia Airlines began a shuttle service between Macau and Hong Kong and which is still going (now operating as Sky Shuttle Helicopters) 20 years later and there are doubtless others.