Ditch Switch
I thought I read also that the aft cargo door was caved in, making the ditch switch redundant. Study of the belly will be valuable, to see if the touchdown load was greater than design, or whether external load and pressure was even considered in the design. It's certainly out of the ordinary.
According to a few who have seen them up close, the Ilyushin is built like a battle ship, and may well survive a water impact intact.
GB