I don't see pop up headlights making a return, ever, due to where automotive design is heading into and how technology needs to be integrated. Going forward I believe it will be more integrated with the vehicles design, more one with the rest of the car, much like in the BMW 100 concept. On a production level into the next couple decades it can't be hard or too costly to integrate:

Fine not the headlights, but the side vents behind the doors seems to be here to stay.