The Predator: What Does The Ending Really Mean?
3. The Kid Is Still A Target?
As the film escalates towards its nostalgic climax that takes the action back to the jungle and Shane Black really gets to play with his Predator toys, we discover that the hunter has chosen a new genetic specimen to use to evolve his species even further.
It turns out that the "McKenna" he refers to as his target isn't the elder figure played by Boyd Holbrook, but rather his son, whose autism marks him out as the next step in human evolution. Presumably, the hunter relays this to his bosses, because he's not working independently.
So that would suggest that young Rory is actually still a target for the aliens. They're still going to want to reap him for their evolutionary needs, after all, so we can probably expect that to be why they come to Earth again.