Conversational interfaces have the potential to allow everyone to use any piece of software by expressing what they want in their own words. This is the opposite of how most applications work today, where users have to translate what they want into a valid sequence of button clicks or commands.
A level 5 assistant could in theory allow you to express in your own words that you want to change your cell phone plan without understanding how to use a clunky web portal. You could book a doctor’s appointment without knowing which specialist is the best fit, or edit an image in Photoshop without hours of prior training. This would radically reduce the friction of interacting with the world around us, and make it more accessible.