Just going out on a limb here...
Aren't there theories of the Annunaki having reptilian counterparts or something along those lines? Would the Predators (who seem to have reptilian elements) make sense as part of all this Engineer/Xenomorph/black goo etc. space god stuff?
Look, I'm not saying they'll go with that, as both Ridley and Blomkamp have stated they don't like mixing the Alien and Engineers with the Predator mythos.
To me though, at this point it seems like it does make sense to do something like that, if we're talking about bridging all the Alien/Engineer stuff with all the ancient astronaut theory (something Prometheus has done).
If the Engineers and whatever other Lovecraftian "things" out there created life, us humans, and the Alien then...?
I'd add that at this point the great creepy mystery of the space jockey from the original Alien has been uncovered, and really are the Engineers (giant albino humanoids) any more mind blowing than something like what Predator culture could be seen as in more detail?