iTunes for Android? Never. Going. To. Happen.
iTunes for Windows was instrumental for iPod adoption, and subsequent dominance of the personal music player market. The difference was that every iTunes for Windows user still bought a high-margin piece of Apple hardware. iTunes for Android doesn't do any good for Apple. The iTunes Store may be a net profit center for Apple, but it's a negligible one compared to hardware profits.
That was 10 years ago. So where is the iPod now? Apple no longer pushes the product anymore. iTunes no longer pushes iPod sales or iOS sales. They could have iTunes for Android if they ever improve their iTunes Radio service, then get Android users to pay for the service (iTunes Match or a rumored streaming service). Perhaps Apple has received enough feedback from Android users requesting an iTunes client on their phone. Did you ever think about that? iTunes stopped pushing hardware sales years ago.