That's waaaaayyy too premature of a conclusion
hence my use of the phrase 'most likely'.
The gear not only folded but went through the floor of the equipment bay. That would have taken some force. If the wheel had fallen off you would have had a scene not unlike the Jet Blue 90 rotated nose gear landing at LAX, where we saw lots of sparks but the gear stayed attached.
If the gear had dug into the tarmac it would have folded or eventually broken off. It is a comparatively light structure and I doubt it would have had the inertia to be flung up through the floor above.
The only thing that doesn't fit this theory is that the wheel appears to be spinning as it crosses the grass which suggests it was in contact with the ground with weight on it long enough to 'spin up' which seems to preclude an instantaneous failure on contact.
Having said that, at over 100 knots, it needs less than a second's contact with the tarmac to achieve a reasonably high rotational speed. Once the axle shatters, the load is removed from the wheel and it will continue to spin for some time.