The New Apple TV is a completely new device that works different to it's previous versions. I am not quite sure why the old Apple TV is not capable of running the new TVOS. Also, the iOS Remote app is not compatible with the New Apple TV as well. To me, this seems strange. Was this done purposely or due to limitations.
Apple has their reason for not making the OS available for the older version and the Remote app available as well. After using the product for a week, in my opinion, this device is half baked. It feels like there is something missing. I don't know if it is the shortage of apps available or simply what is Apple attempting to replace. Is this Apple's version of gaming console, and/or cable box replacement. All I know, is that, the hype did not last very long. After a few days, my New Apple TV just became a $149.00 screen saver.
After a week, I returned the New Apple TV. I feel, in the near future, when Apple figures out what this device should replace, then I'll considering buying one again. I am not losing faith in Apple, but simply think they are revealing products sooner than they want, because of the business need.