I think Grim vs Bigfoot would be a great fight and makes alot of sense right now. Both are coming off of loses and a win would pole vault one of them back up to the top.
As for Fedor the logical matchup is Overeem for the belt, but I have a sneaky suspicion that Overeem will never accept a fight with Fedor inside the US. So Werdum is really the only fighter left that deserves the fight.
I would like to see fighters like Herman, Monson, and Yvel come to Strikeforce aswell and add depth to the HW division.