Here's the thing... Disney doesn't have to generate D+ originals to have D+ content...
The overrotation all the services have right now is the notion that people only want a channel for the newest shows. I think most providers are flopping terribly at getting people to watch the historical content they have... content that people LOVE they just don't know it's there, forgotten, or it's just too buried to be bothered with.
I expect as the space matures, you'll see the streamers invest a lot more in their app, profiles, and content suggestions. These are all areas everyone short of Netflix is absolutely horrible with right now... and is the backbone that others like youtube, instagram, etc excel at. If they're smart they'll fix that and get back to keeping accounts happy by having them farm their existing content libraries far more than they do today.
Less we forget the majority of the TV time during the day was filled with non-original, often repeat shows... not blockbuster original series 24hrs a day. Streaming needs to do a better job of feeding couch potatoes to keep the stable customer base instead of trying to endlessly attract them with the latest sweet.