Whatever it looks like, I truly hope they don't f**k it up.
Personally, I wouldn't show the Predator homeworld. Creatures/aliens are always more interesting when you don't explain every last damn thing about them. Why does there even have to be a homeworld? I wouldn't be against the idea of Predators being a species that once had a homeworld, but now only remain with a few remaining nomadic ships/clans that do on other planets what they used to do on their own : hunt.
Things I would like to see if I were forced to insert the scene:
I would expect the world to be primitive, lush, and hot, with some other sorts of nasty and violent indigenous life. Pretending like Anderson's AvP never happened, both Predator movies established very strongly that Predators prefer it H O T. So, no f**king ice. No cold. It can be that simple. Vegetation + heat + vicious indigenous species.
Things that would make me go apeshit angry if they included in a predator homeworld sequence:
-Anything that even remotely resembles a f**king pyramid.
-Female Predators (they may exist in comic books, but it would look retarded on screen, don't even get me started)
-Predator "civilization" : I don't want to see any f**king Predator universities, Predator starbucks, or Predator ship building factories. They are a violent, primitive creature that mysteriously has advanced technology. Explaining where they got their technology or how they developed it would take be disappointing no matter how you did it.
-Predators-in-training: I don't want to see another overweight, clumsy, dipshit teenage predator as long as I live. Leave the female and youth predators to the lore of lousy comics and Paul Anderson movies, respectively.
In summary: I just hope they keep it brief, simple, and don't try and explain too much.
