What would be the point of flying a jetski or quad bike to open water at great expense when they typically launch off the beach or a boat ramp for nothing? As Onetrack said, it's very hard to see any commercial justification for a new amphibian, at least in Australia. As a tourist transport in the Caribbean or the Great Barrier Reef it might have more value, but there are floatplanes that already service that market, so it would face stiff competition.