MovieHole, has posted an interview with Director Robert Rodriguez. In this article, Predator 3, or Predators as he calls it, is mentioned:

"Oh, "Predators", yes we're the "Predator 3", it's call "Predators". It was back when I was doing "Desperado". I wrote "Desperado", it was going to get made like end of September, and then "Last Action Hero" bombed, so they said we're not making any movies for a year, like next year. So I was like what am I going to do until then? So I took a writing assignment, and one of the writing assignments that was out was "Predator" sequel. "

Read the article here.

After reading the previous article i looked into Pred 3 a bit more. According to IGN, there are currently 3 scripts. One called Predator 3: Deadlier of the Species, Predators and Predator 3.

Predator 3: Deadlier of the Species is written by Sam Park, and feature Dutch stuck in LA during a blizzard and a Predator Huntings him.

The second Predators, is set in the 17th Century, on a boat, and the crew have to fight the predator using week weapons. Maybe this is where the Pred from Predator 2 got his gun from?

The last, Predator 3, being the old rumored script where Dutch and Harrigan would get taken by the predators back to there homeworld.

Check It Out.