Instant action Siri would be nice. Instead of spinning ball it would create the reminder and be done with it.not only offline siri, but much improved Siri, especially on the voice recognition end.
I would also greatly welcome Siri API, as to allow for me to say "Play music on spotify" or whatever and it would start to play. Now, while driving, I can start spotify with siri but still have to take my eyes off the road for finding the playlists and play buttons etc.