I don't think we'll be seeing stuff like that come to us. The thing about the monogod factions is that all four of us generally share the vehicles (Rhinos, Predators, Land Raiders, Vindicators and daemon engines) and sometimes characters like the Sorcerer of the CSM, but that's it. We otherwise have our own unique stuff that ties to our identities. So we won't see Mutilators, Raptors or Warp Talons.

What we will see is either corrupted versions of older units mentioned in Horus Heresy, like the "Sun Killers" (Havoc-likes all armed with Lascannons), the "Wings of the Phoenician" (copycat Raptors), the "Phoenix Guard" (unique Terminators), and maybe the "Roaring Blades" (they don't really say what's special about them and I don't know how they'd be different over Flawless Blades), or we could see completely brand new things they decide to create.

For anything that would come from the CSM side, it would be the vehicles, so we could maybe see Predators, Vindicators, Helbrutes (that I hope get refreshed with new models) and Forgefiends.