The only intent that really matters is the one portrayed in the final cut. The filmmakers cut that scene for a reason, whatever it might have been, choosing instead to leave the Kryptonians' fate ambiguous when they could have left it crystal clear. The only logical assumption we can make based on what actually appeared in the final cut is that those three probably died from such a fall, given that it was never followed up on and we never see any official evidence to the contrary.
Well watching the three supervillains get carted off by the police at the end DID look pretty darn silly, so I can definitely understand why Donner decided to cut it out.
