Interesting article, thanks for sharing. The question posed is off a tad, it should really ask "when will they share airspace". I don't think there is a chance they won't, just a question of when.

We've already seen technology and automation reduce the need for more people in the cockpit, the discussions now surrounding drones pertains to commercial use for product deliveries, agricultural, and even filming purposes. Eventually we'll see one pilot in a plane, and then...no pilot. I don't know if it will happen in my lifetime, but that's coming. There are already a couple of mock ups out there.