The entire iTunes catalog available for streaming would be a killer feature. Where did you see hear that the entire catalog would be available to stream?
https://www.apple.com/pr/library/2015/06/08Introducing-Apple...
Also alluded to here in the Apple presser:
> whether from the iTunes Store® or ripped CDs — your music now lives in one place alongside the Apple Music catalog with over 30 million songs.
https://www.apple.com/pr/library/2015/06/08Introducing-Apple...