The killer app for me is ANY size screen in a smallish mobile package. And that was demoed in the WWDC presentation.
Anybody want an even bigger MB? An even bigger iMac? An even bigger iPad? An even bigger iPhone? Conceptually, ALL of them could be "in there." I doubt Apple will ever make even a 20" MB (will we ever see the 17" again?)... but this can deliver the illusion of one MINUS the weight and unwieldiness. Ever wish your biggest screen desktop experience could be anywhere you happen to be? Perhaps this can replicate it... on the plane, on the train, in the Uber ride, at the hotel, etc. Am I the ONLY road warrior who often wishes the big screen Mac back at home/office could be there- wherever "there" happens to be this week- when on the road? Here's a very tangible way to get that- the ONLY practical way.
All tech players are working on ways to deliver bigger screens while clinging to mobility. That objective is yielding attempts at FOLDS, at ROLLS, etc. Perhaps Vpro is an Apple cut at the same? And instead of delivering a rigidly fixed-size screen when unfolded or unrolled, this ONE device can deliver ANY size screen... as small as a phone screen and as big as IMAX: no creases, no scaling weight with size, etc.
If using it as a laptop (BIG) screen works as good as it appeared in the demo, Vpro may be my next "laptop" (screen). Why be limited to "up to" 16" anymore, when a MB could be 20", 30", 40", 50", ultra-wide, 2 screen, 4 screen? And deliver any of that without the weight of aluminum, glass and overall heft.
And that's just ONE "killer" app IMO. With a little imagination about a device that can effectively show our eyes ANYTHING paired with devices that can play ANY sound to our ears, there is a LOT of killer apps to be created and delivered. "Think different!"