How would this be tooled? A chargeback, a deep link to the cancel page, an API connection between bank and subscription?
Chargeback is easy because it's under the card co's control. Deep link would require knowing the cancel page of every sub, plus handling auth factors. API connection would two way integration, with scoped auth between every bank and every service. Hopefully managed by an SI or aggregator, but the business model sounds hard (the bank doesn't mind the chargeback, the SaaS doesn't want the cancelation, so who pays?)
Wow... this is so validating. I worked on a project I called "Buzz Me Up Scotty" (Or something like that) to do a very similar thing. Just glad someone proved the vision.
Super interesting, I added this (albeit way less pretty) to my personal site and generally got poor reviews. That being said, I'm really enthusiastic about the idea.