If they add positioning, this product becomes Magic Leap without the visuals. I don't think they see this as a music device, they see it as a new platform for audio. Interesting things start happening when people start leaving one or both in their ears all day. Arrival times in your ear at the bus stop. Ask Siri for a price check while at the store, etc.
A cable to your phone makes the earbuds hard to forget. This makes it easy, but the design details have to be right for you to truly forget they are in.
I know "forget they're in" doesn't sound like a groundbreaking feature, because it's not connected to any obvious technical challenge, but I think if they succeed at that it would in fact put these in a new category.
Positional audio would seal the deal. You can walk around your kitchen and it would feel like your invisible conversation partner was in the room with you.