I don't know if this announcement has much of an effect on developers. I'm sure there are some situations where developers are making some money with affiliate links, but it's not something I've ever researched. But app developers aren't the only ones using the Apple affiliate link program.
The editor-in-chief of Touch Arcade, a website that drives tons of traffic to the App Store, is understandably upset about Apple's announcement yesterday. The post shows just how much Touch Arcade has had to adapt over the years to make their business model work. My guess is the dust will clear and they will adapt again. They've shown the same resiliency in the past.
Apple Kills the App Store Affiliate Program, and I Have No Idea What We Are Going to Do. by Eli Hodapp