I was surprised that I didn't see a thread on this here; Green car reports apparently put together an article on why the Model X is late, blaming EPA rated ranges, towing issues, and the Falcon wing doors:
Why Tesla Model X Electric SUV Is Late: Range, Towing, 'Falcon Doors'
Walter
Why Tesla Model X Electric SUV Is Late: Range, Towing, 'Falcon Doors'
Walter