Apple today sent out an email to registered developers, noting some changes that are coming to the App Store. One of the two listed changes has to do with quality apps:
Quality is extremely important to us. We know that many of you work hard to build innovative apps and update your apps on the App Store with new content and features. However, there are also apps on the App Store that no longer function as intended or follow current review guidelines, and others which have not been supported with compatibility updates for a long time. We are implementing an ongoing process of evaluating apps for these issues, notifying their developers, and removing problematic and abandoned apps from the App Store.
We noted back in June that the iOS 10 beta will warn users when attempting to use an app that hasn't been updated with a 64-bit build. Any new or updated app submitted since June, 2015 is required to have a 64-bit variant, so if you see that warning, the app you're using hasn't been updated in some time. It's quite possible that that is one of the things that the company is referring to when it mentioned "problematic and abandoned apps".
Once iOS 10 launches, there will only be three 32-bit iOS devices left supported - the iPhone 5, 5c, and fourth generation iPad. There are no supported 32-bit Macs, and there haven't been any for some time.
The firm did make changes to its review guidelines, which apply to subscriptions, iMessage, and SiriKit, most of which couldn't even apply to an older app. There is, however, a policy under subscriptions that says it "must provide ongoing value to the customer." If a developer isn't keeping up with an app that offers such a service, it could be "problematic".
Apple will also be cracking down on longer app names, which will now be limited to 50 characters. The reason is that, "In hopes of influencing search results, some developers have used extremely long app names which include descriptions and terms not directly related to their app."
All of these changes will go into effect on September 7, which is also the day that the company is slated to announce its next iPhone generation. Following the event, the firm will likely release the final GM seeds of iOS 10, macOS 10.12 Sierra, watchOS 3, and tvOS 10, so it makes sense that that would be the time to implement new policies.