Despite being a Now TV customer, I think that its extremely short sighted of Now TV/Sky not to have a more broader reach of devices for the Now TV app to be on.
Considering that Amazon Prime Video amongst others aren't on any Now TV device is stupid in my opnion. Even though Netflix has finally arrived on Now TV devices, this did in no way make me think hmm I could do with getting a Now TV box/stick.
Personally I prefer the interface of Amazon Fire TV over Roku. That being said I have an LG TV which is where I get my Now TV fix, but I recently purchased a Amazon Fire TV stick for travelling, as the device has apps and app functions that Roku and Now TV do not.
So to hear that there are no plans to add Now TV to Amazon devices is very disappointing.