* Medical settings in which patients are slowly losing the ability to move or communicate, being able to look at a keyboard to type messages to your loved ones or perform basic actions (e.g. turning music on) make a terrible situation a tiny bit better.
* Entertainment/gimmicks: you go to Disneyland and you put on a cap/helmet and suddenly you can interact with objects just by looking at them (they have a flickering light next to them that pulses in a certain binary pattern) - it's like magic.
The second usecase is very difficult today though, the tech that I worked with (+5 years ago) needed to be trained for every new user and a training time of 10 minutes was considered very short. That of course makes the Disneyland usecase more difficult. Also you need to make sure you don't move or blink too much - maybe fNIR has less issues with that.