I think The Rock would be ideal for a Predator 3.
Other than that, I'd welcome anyone that survived Predators 1 & 2 and AvP.
If i was going to make AVP3 i would make it based on Aliens/Predator: Deadliest of the Species. I would have Jamie Chung (From I Now Pronounce You Chuck and Larry) to play as Caryn Delacroix.
A movie based on Deadliest of the Species would end the franchise. No one would accept the idea of an Alien Queen working with a human and a Predator, even if it was to save her little chestburster-to-be. And all the Predator action in the first 100 pages is from flashbacks.
You might be able to use a few story elements as inspiration, but the overall plot is appalling.