It seems there are differing requirements and, certainly opinions. I guess we will have to wait until the 29th or longer to know (assuming the Founders aren't going to measure their vehicles). If there are Signatures delivered on the 29th, then there is some hope of resolving in 2 weeks.
I measured my Audi Q7. With the third row stored flat and the second row passengers comfortable leg room, the storage space is 45 inches x 45 inches. Since I have the front and rear air handlers, the space side-to-side is slightly less than a single air conditioning Q7. That holds four sets of golf clubs (drivers diagonal), with four passengers. That is my requirement. I sometime use the Q7 to transport larger items requiring the folding of the second row seats. That give the Q7 45"x80" cargo floor.
If the Models X can accommodate four sets of clubs and bags and golfers (frunk and rear), then I am good. If the space with the 2nd row moved, twisted, ducked, raised, spooned or otherwise moved, revealing close to 80", I am good as well. My expectation with any vehicle is equal to or better than my existing. I will give Tesla slack to have a Environmentally responsible vehicle. The few times I need to move 4x8 stuff, I'll rent a Home Depot truck for $19 bucks.