If I’m being honest, it won’t be anytime soon. On the device Apple TV, it doesn’t even have the updated Now TV app and that was after 9 months of trials.
My guess is that Now TV devices will be a thing of the past.
I have the ridiculous situation now where the Apple TV app is on my Google Chromecast with Google TV but not on my Sony TV, but Now TV is on my Sony TV but not my Google Chromecast with Google TV.😣
Quite how companies like Now TV benefit from restricting their offering to certain manufacturers devices (when they are all running the same operating system) is beyond me. It is certainly not a technical limitation in the case of Google TV.