Well, if that is the death of Rover, what follows then, must surely be the opposite of death, and that is - the Birth of Rover.
I'd never thought about this before. But this makes as much sense as the death of Rover. But of course what the viewer sees die in Fall Out, is but a fragment of the Village Guardian, much of which would still remain in the containment area somewhere at the bottom of the sea, which Rover is born of.
Be seeing you