What Cortana needs to be is like Siri and Google Now except good. Siri has Wolfram Alpha, but otherwise is not very good. Google Now is fast, has good voice recognition, and has some good features (where my car is parked, stores in malls, etc.), but has a lot of annoying features like delivering news stories to me when I've already searched for them and creepy stuff like tracking my flight from an email in my inbox. If Microsoft can continue to expand the third party app support and add in a reliable and visually appealing way to get information (Google has cards and then searches, MS should make the information show up in a box like Siri and show the previous stuff in the "conversation" and make searches a swipe away) and add in a Touchless Control style feature for supported devices, Cortana will become the voice assistant/voice... thing of choice for a lot of people.