Will asked a fair question, "What gives you the confidence to quote "60-120 mph" ??"
That is pure conjecture considering the terminal velocity of a human (about 120MPH) and the wings. I doubt it'd hit flat at 200 MPH with both wings present. (With only one wing it would not hit flat at all.) It might have hit faster if the pilot had been in a poorly controlled dive and managed to try to pull up as he saw the ocean. That would account for the flat or almost flat attitude, the tail breaking off as it did, and would likely give a faster velocity vector when contacting the ocean.
If I understand the construction of the pressure vessel and the interior the pressure vessel does not support much weight at all. That is all handled by an interior cabin construction. That way the pressure vessel would not be punctured by a lot of small holes supporting heavy weights. Thus it would be sort of like dropping a cigar tube on its side with the cigar in it. You'd get crumpling on the bottom that hits the ground. But the top would not crunch down. That's an extreme example. But it gives the idea behind my thinking. Mass as well as deceleration is needed to crunch the cabin.
Some evidence indicates a break near the front of the wing. That is how the galley and other parts "escaped". And it explains the crew rest facility pieces. If that happened before the rest of the fuselage crunched with its circular integrity removed you can explain the distribution for the recovered passenger bodies.
The chief arguments regarding a break-up in mid air involve getting the debris to where it was found given the ocean currents and the missing items you'd expect to see from a breakup. This would be items of luggage from the hold rather than the sparse couple things found that are generally overhead bin items.
The breakup scenario also requires the plane to remain in a relatively stable attitude until after the last message. It also requires the plane to remain enough in one piece to hit the ocean more or less flat. And you have to break off the VS in the mode seen. (Remember my demo concept of pulling pages out of a three ring binder. You can figure out how you pulled the paper out by the tear patterns. And the VS is very much like that piece of paper right down to the "three ring binder" mounting.)
I'd believe breakup in the air if you can prove God or weather could swat at a plane mashing its tail forward and up without leaving marks on its rear edges.
JD-EE