Roughly 80% of App Store Revenue are from Gaming. I would not be surprised if 95%+ of those Gaming Developers does not fall into Sub $1M Annual Revenue. What is left are Apps which many falls into this category. Even if half of the remaining 20% of App Store revenue fall into Sub $1M AR, Apple is only looking at a maximum of 10% hit from its Total App Store revenue.
This is even better than my idea of splitting Game into a separate Game Store and retain its 30%, while letting App Store with 15%. This new system gives all the incentives to low revenue developers which really needed the help, without sacrificing more revenue than needed.
Although I really wish they had done this earlier, and now it is looking more like damage control than anything. And it still doesn't fix their App Store review process becoming increasingly hostile. Along with many other complains.
Edit: I am reading into it, it seems like once you cross the $1M this year your next year will remain on the 30% bracket. And only if your next year revenue drop below 1M will you be move back to 15% the year after.