Decoding the marketing speak, I'd say Google makes more money off its other programs, so Google is axing Affiliate Network in favor of those. Publishers are expected to move to AdSense CPC/CPI, and given how little competition there is, few customers will leave.
“we’ve made the difficult decision to retire Google Affiliate Network and focus on other products that are driving great results for clients.”
http://googleaffiliatenetwork-blog.blogspot.com/2013/04/an-u...