Solarpunk technology

Realistically, the current air travel infrastructure wasn't built on tourism, it was built on serving business needs - freight, personnel movement, meetings, sales. You're talking about replacing that infrastructure, or at least competing with it, while also being dependent on rail infrastrcuture...

In order to grow this airship system will have to offer some substantial practical advantage over the existing one. The thing is, if I'm shipping something and speed isn't important then rail/truck is fine and I don't see airship freight being cheaper than that. So if the airship doesn't fit the fast/expensive use case, and it doesn't fit the cheap/slow use case, then what is the competitive advantage?

As far as capacity goes that's just a matter of building bigger airships

There's a practical upper limit to how big these things can be. Regardless of fancy new structural materials, it's a giant gasbag... the larger it is the more of a problem any crosswind is.

using relatively cheap hydrogen instead of helium as the lifting gas.

It's going to be a long time before any safety oversight group gets on board with this.