4 of the 6 are those who did not make it to the team merger in TDI (Beth, Harold, Courtney, and Justin). Not to mention 4 of the top 5 are gone. Probably the writers want to give some of the other characters a chance to be developed. I know Harold, Beth, and Justin has been getting a large amount of screen time compared to some of the other cast mates, similar to how Owen, Gwen, and Heather have been relatively dominating during TDI.
Based on that, I'd say Duncan will be gone soon, either they kick him off as the 2nd to last Gaffer so it will be 4 Grips to 1 Gaffer in the top 5 similar to how they did it in TDI (4 Gophers to 1 Bass) or they kick him off in the 4 spot, just because they seem to like repeating themselves in some weird sense of irony (Trent was eliminated due to Gwen and had Izzy and Courtney not come back he would of been in 11th place, DJ being eliminated during a horror episode, Izzy being eliminated twice).
My guess for the final 3 based on that is basically villain, male, female. So Justin is in, where he'll get his final comeuppance on the 2nd to last elimination like Heather, Harold, since I predict he will be the final male other than Justin, and either Beth or Courtney, though probably aiming for Courtney, since they could probably wring out more drama by doing a repeat of what Heather did to Lindsey.