I think it is wrong of discovery channel to move it’s more popular shows exclusively to discovery. As a cable TV subscriber, what would be the point of paying for cable if every channel ended up doing this? Disney has done the same but it was able to gain subscribers by creating original content, not by holding its popular cable shows hostage.
They need to allow cable subscribers to continue watching the shows that have been airing on cable for years and not make them only available in the app. One possibility is giving discovery subscribers the ability to watch the shows in advance and then release the shows onto cable.