Some loads simply don't fit on trucks, or rather on the roads that the trucks have to use. Heavy lift airship would operate in a market segment that does not even exist without them.
Big transformers are now limited to boat transportation, and it's a constraint on grid design. I assume this is also the case for other industries that become river bound but wouldn't necessarily be so if not for equipment transportation. So this could be a game changer (more so I think than this faster than boat slower than plane thing).
Wind turbine blades is the obvious one. On-shore turbines would be much larger (which btw implies lower rpm, which implies being less annoying) if they were not constrained by land transport.
So I'm just curious what is that segment and how large ($) can it be? What cargo exactly would it be transporting?