[dstein]

Google almost certainly does not intend to suddenly start charging for Android once iOS and Windows7 are out of the picture.

More likely their intention is to keep it free, but with additional "conditions" such as Google search being the only way to find information. Mandated use of Gmail, Google Docs, Calendar, Contacts. Heavily integrated Google Plus social features like chat, blog, and photo sharing.

Google won't need to charge for Android because there will not be a way to avoid a Google tentacles if you use their OS. Google is trying to burn down the ecosystems of it's competitors with free products and make money by being the gatekeeper of your every activity with a smartphone.