Having spent time operating a Combined Harvester for several years I can tell you that most fields are flat, level and fairly solid. If the wheels break the surface, all the better. If the wheels come off, so what? If the engines gouge into the ground and get ripped off, great!
4th APR 1978. B737. The right main gear collapsed and the no.2 engine was torn off in the slide. The aircraft came to rest 300m past the runway end and was destroyed by fire. There were no fatalities.
17DEC 1978. B737. The aircraft belly landed in nose up, left wing low attitude, on the centre line of the runway. It slid for 3080 feet, hit a boundary fence, crossed a drain and ploughed in rough terrain negotiating with small boulders and came to rest. Fire broke out on impact. One passenger and 3 maintenance workers cutting grass were killed.
17FEB 1981 B737. The 737 left the runway surface at 900ft past the threshold and skidded another 1170ft before coming to rest 115ft to the right of the centreline. The aircraft was destroyed but there were no fatalities
25MAY 1982. B737. The aircraft landed heavily in a rainstorm and broke in two.The crash killed two of the 112 passengers.
This is just a review of accidents involving B737s over a few years. They all indicate that survivability rates even from a severa and catastrophic impact are greatly enhanced if the aircraft remains upright, regardless of how quickly the fire services arrive.