This is the big difference between streaming and having channels. Quite often the media companies licensed their content out to other broadcasters, or when they did have their own channels, the content available on them was severely limited. Disney's (ABC's) main shows were licensed to other UK broadcasters, so were never available on Disney's own channels.
If Disney, Comcast and the others do streaming properly, the streamers should be:
1. Global.
2. Contain vast libraries of content permanently available.
3. And cheap would be nice too.
Disney has said their Disney+ service will be cheaper than Netflix, but it all depends on what's on their service.