1. Launching apps.
2. Searching developer documentation with Dash. I can pop up Alfred and type "dash nsstring" and it'll show me the docs for that class.
3. Clipboard history. If I type "clip" it shows me everything I've copied to the clipboard in the past day. I can filter that by typing. Pressing return pastes the selected entry.
4. Hotkey actions. The main one I use binds cmd-shift-5 to a custom script that starts the GUI action for taking a screenshot of a selected area of the screen, then uploads the resulting image to my web server and places the URL on my clipboard.
5. Searching Google by just typing stuff into the Alfred bar.
6. Invoking Wolfram Alpha by typing "w stufftocalculate".
7. Searching Wikipedia by typing "wiki stufftosearch".
Of those, I don't think 2, 3, 4, 6, or 7 have any hope of being replaced by Apple. 1 could, but on the other hand this has in theory been supported by Spotlight since 10.4, and it's just been too unreliable and slow. I doubt they'll finally get their act together on it now. 5 is the only one that seems likely to be obsoleted by Yosemite, and that's a minor one.