Backstory: I'm currently at SubSummit and from talking with merchants here, I'm amazed to find quite a few sell a progressive experience to customers. Most are educational that walk students through a learning process. Additionally there are games and experiences like Hunt a Killer :)
The Idea: An ecommerce platform for selling episodic products.
Deep Dive: You would build an ecommerce platform similar to cratejoy but it would track the customers shipment progression and allow merchants the ability to build out paths and sequences of products.
Validation: I've worked with Hunt a Killer for over a year and this would solve a lot of our tech/fulfillment issues. This project is a large undertaking, you could get a few companies to commit before you build it.
Monetization: Similar to other SaaS platforms, you would bill customers based on their volume.