Apple is going to be introducing a new method for e-book companies to be able to charge for subscription fees. Currently, Apple takes a 30% cut of subscription fees on the App Store, but now, if a customer stays subscribed to a service for multiple years, Apple will only take a 15% cut, leaving 85% of the profits for the e-book company.
I think the obvious beneficiary of the new app subscription policy will be Amazon and their Kindle Unlimited program. This makes the most sense to me, because the vast majority of their e-book catalog are indie authors and small publishers. These are the type of people that would really dig getting more exposure on the Apple platform, where statistically the average customer spends more money on in-app purchases and subscription fees. Amazon would likely have to adjust the royalty rates on the Apple platform, in order for the company remain profitable.
Scribd is one of the few e-book subscription sites left standing, after Entittle and Oyster went bankrupt. They currently offer 3 books and 1 audiobook, plus access to sheet music, documents, and Scribd Selects for $8.99 per month. I think they would be able to generate more revenue by locking in users for a one year subscription and offering them a discount.
The new subscription options should go live in a couple of months, while Apple puts the finishing touches on the new system.