You are right on that we're developing small cargo ships at about 1% of the largest containers ships. However, a comparison to the largest container vessel is not fair. Our concept has 160 twenty-foot containers (TEU), which is the same as fourteen 747 cargo airplanes and can complete on freight duration with airfreight. Most air freight takes 3-7 days despite a 12 hours in-air transit time, and the remaining time is sitting around airports. We can deliver in 6 days across the pacific ocean, and port wait times are minimal because of our small vessel. Though, if you pay 10x the premium, you can get FedEx or DHL to deliver up to a 1 ton anywhere overnight. Airfreight moves 35% of the world's cargo value and is a $100b market, and a single airplane is only 0.06% capacity of the largest container ship. Hardly niche.
If the hydrofoils ships are too large, they will spend too much time filling the vessel rather than delivering point-to-point cargo, improving the service. Most ocean lines make 4-6 stops at ports, while a small foil ship can load quickly and make no stops, thus significantly reducing the door to door duration.
Correctly pointed out, hydrofoils do not follow the same scale laws as standard buoyancy vessel. The amount of cargo that can be delivered increases with the cube of the length assuming all else scales, meaning the fuel and crew cost per container decreases drastically with larger ships. That's why we see mega-20,000 TEU-container-ships. Hydrofoil ship lift capability scales linearly with plan area of the foil, so we don't gain much making them mega-ships.
Airships are cool. I'd like to see one built.
https://en.m.wikipedia.org/wiki/Boeing_Pelican
Having said that, hydrogen airships are probably the way to go due to abundant gas, high lift, ability to compress as per airlander.
https://en.m.wikipedia.org/wiki/Hybrid_Air_Vehicles_HAV_304/...