Theoretically, there should be a gap of applications that are too niche to start a business off of and, prior to AI, too complex for an individual to write on their own, which is probably where any future for indie apps lies. I don't know of any examples of that sort of software though, does anyone know any?
Applications built using deterministic code to work might just not be a thing people need to pay for anymore.
Maybe work relating to training ML can still have value? The compute cost and time involved in it add to the moat.
Key takeaways: People don't like subscriptions for on-device apps, and people really don't like telemetry.