The apparent leak also discussed how developers would get paid. Apple would divvy up subscription fees based on how often people play a studio's games, theoretically rewarding those who make particularly compelling titles that keep things fresh with regular updates.
You might even hear about the service relatively soon. The sources mentioned that Apple could talk about its plans as soon as its March 25th event, although this isn't guaranteed. If not then, it might prefer to talk about game subscriptions at WWDC in early June. That latter option makes the most sense in our eyes. The March 25th gathering is expected to focus primarily on movie and news services, leaving little room for early talk about another service. Also, Apple may want to recruit developers for the service straight away instead of teasing them a few months early.