"According to 9 to 5 Mac, sources indicate that instead of having a standalone Game Center app, the scoring and ranking functionality will instead be found solely inside games that have integrated the social gaming feature."

Online gaming is largely about statistics for marketing, and what better way to collect that data then to integrate gamers with social media. This borders on invasion of privacy. 

http://www.ign.com/articles/2014/03/16/apple-may-abandon-game-center-in-ios-8