@Anonymous User
It is very unlikely that it will become an app on the Now TV stick.
The focus of Now TV seem to be switching from providing a device to focusing on the service itself. Which the deal with Amazon will indicate this to be true, since Now TV has finally become avaliable on Amazon Fire sticks.
If you want to find out for sure, you can drop an email to customer support. Address in the below picture.

FYI that I do not work for NOW, just a NOW customer trying to help