A friend of mine does event photography for swing dancing. He's looking at getting one because it's really hard to catch focus when things are moving so quickly (in dimly-lit halls). There are photography niches out there where features like this can be a necessity.

Another use-case I've heard about was wedding photographers using depth of field as a Ken Burns-like effect for videography or on their webpage.

Both are narrow use-cases, but I too find the technology fascinating and hope it finds a sustainable use-case.