The falcon wings - rather the gull wings - have been around forever. The problem is that you need a significant roof height in order for them to open.
Ever tried parking in a cramped multi-storey car park? You'll be crawling out of your car via the foot well. It's the main reason they've never taken off, but I'm guessing only the rear doors are like this.
FWIW, the SLS gets around this by having explosive bolts in the hinges that blow when the car is past something like 90˚ in orientation and has a velocity of 0 for more than N seconds. However, the SLS is a $300k car, so no expense is spared. That solution might be a little less feasible for a car that costs what the Model X will.
I dunno, given the other story today[1] about the Tesla S blowing away everyone else in safety tests, I wouldn't put it past them to have considered escapability after a roll-over in the X.
Ever tried parking in a cramped multi-storey car park? You'll be crawling out of your car via the foot well. It's the main reason they've never taken off, but I'm guessing only the rear doors are like this.