I don't see why it couldn't be a Devestator upgrade kit, people are presuming to much to think that they will do another Crossfire set, they might simply go for the option they did with the Arielbots and add some fists and feet.

Or maybe they will add two new bots to replace the duplicate arms, I don't see them replacing the torso with two new bots outside of fan fantasies. Fans Projects seem to be about upgrading rather than outright replacing everything with more accurate stuff, I think if they do add new combiner bots their focus would be on replacing cloned limbs.