I would add better integration with mobile devices beyond bluetooth. I'm thinking a startup could create hearing aids with self-tuning apps that employ spectral analysis and echolocation capabilities for improving situational awareness of the wearer.
High-end hearing aids already do this on-device. I don't think it would be a great development to require hearing aid owners to own a smart phone and load an app onto it to be able to get full functionality out of their hearing aids. If the functionality needs to be externally configurable for some reason, provide an external controller that comes with the hearing aids.
