On one hand, the agreement dangled the loss of “future business opportunities that Apple and/or its affiliates may present to you” as a potential consequence of violating or not signing the agreement. On the other hand, signing and following it could lead to months-long delays in making accessories like cases available, during the time of year when those cases were most needed and demanded by customers.
Frequently, accessory makers manage to obtain the specifications of future Apple products in order to have cases and other accessories ready to launch as soon as Apple releases its latest device. These prototype cases often leak online revealing information about the upcoming device. Sometimes accessories makers get it right, sometimes they are way off. Either way, Apple is looking to clamp down on leaks and these vendor agreements are one way it hopes to do so.
Accessory partners are now banned from seeking, obtaining, or relying upon advance specifications for future Apple products. After consulting Apple about the agreement's language, one developer said it goes as far as prohibiting the reading of any web site or newspaper that even discusses upcoming Apple products, including The New York Times.
Apple typically releases its manufacturing specifications after announcing a device. This gives makes it nearly impossible for accessory makers to design, prototype, manufacturer, and ship a case in time. Vendors that refused to sign the agreement were told their products would be banned from Apple's stores. Some vendors that signed had their products removed anyways but apparently are still bound by the agreement which says:
“…should Apple find that, prior to the release of a product, you have sought, obtained, or relied upon specifications of that product from sources other than Apple, Apple may choose to exercise its right to take action against you, which penalties can include, but are not limited to, Apple choosing not to stock your product in our stores.”
Notably, Apple is said to have removed around 60-70% of third-party cases from its retail stores, perhaps to make way for the Apple Watch. However, the company did release leather and silicone cases for its devices in 2014. This agreement and reduction of third-party cases in its stores will push more customers towards its offerings.