And the final scene:
Sonny: (looking down at the NS-5s being herded away) What about the others?
(the scene changes to show Sonny's feet making footprints in the sand as he walks towards the plaque Spooner placed Lanning's holo projector on)
Sonny: Now that I've fulfilled my purpose, I don't know what to do.
Spooner: I think you'll have to find your way like the rest of us, Sonny. That's what Dr. Lanning would've wanted. That's what it means to be free.
(cut back to reveal Sonny standing in front of the NS-4 storage ground. The NS-5s are all walking into the storage crates, but one by one they see Sonny standing on the hill, and stop moving, staring at him.
"This is the place where robots meet. Look. You can see them here as slaves to logic. And this man on the hill comes to free them. Do you know who he is?"