Even if Apple manages to keep 99% of all transactions, simply having open competition will open the door to all sorts of improvements.
You could decouple distribution from payment processing. Have an "app store" with only free apps, but they can have in-app purchases if they handle their own payment processing. This is basically just a CDN. We already have a very mature and open market for CDNs, and they're very cheap.
We also already have a mature, slightly less open market for payment processors. Stripe charges about 3% and provides almost all the features the App Store provides for 10x bigger fees. The one feature most people would probably miss is centralized subscription management, but there would be nothing stopping Stripe (or someone else) from offering the exact same basic feature, charging way less than Apple, and still making a huge profit for themselves
You could decouple distribution from payment processing. Have an "app store" with only free apps, but they can have in-app purchases if they handle their own payment processing. This is basically just a CDN. We already have a very mature and open market for CDNs, and they're very cheap.
We also already have a mature, slightly less open market for payment processors. Stripe charges about 3% and provides almost all the features the App Store provides for 10x bigger fees. The one feature most people would probably miss is centralized subscription management, but there would be nothing stopping Stripe (or someone else) from offering the exact same basic feature, charging way less than Apple, and still making a huge profit for themselves