For some reason, Sony announced today that they are going to ditch support of PlayStation Now on all of their devices except for PlayStation 4 and the PC. This change is slated for August 15, 2017.

The following devices will no longer have the PS Now service at that date:
• PlayStation 3
• PlayStation Vita and PlayStation TV
• All 2013, 2014, 2015 Sony Bravia TV models
• All Sony Blu-ray player models
• All Samsung TV models
• Additionally, 2016 models of Sony Bravia TVs will be discontinued on April 1, 2017.

Well, that's weird. Why are they doing this? Brian Dunn, the Senior Marketing Manager for PlayStation Now provides some explanation.
After thoughtful consideration, we decided to shift our focus and resources to PS4 and Windows PC to further develop and improve the user experience on these two devices. This move puts us in the best position to grow the service even further. If you use any of the above devices, we want to give our heartfelt thanks for your support, and we hope you’ll continue with us. Remember that all of your PS Now cloud game saves can easily be accessed on both PS4 and Windows PC.

It's quite likely that Sony found only a handful of people were actually using the service on those devices and deemed them not worth supporting. To those on the devices that will no longer have service, make sure you cancel your subscriptions before they auto-renew ahead of the cutoff date.