Forge World Jigsaw Teaser

In their latest newsletter, Forge World has released their traditional teaser for a future miniature. This year, they're doing it as a jigsaw, rather than one big "reveal".  This is part 1.  The other parts will be released progressively.

So, the question is, what could this be?!

From the base and size of the lower leg, I'm going to go out on a limb (bad pun there!) and suggest its a terminator.

Now, if its a terminator or similar, what would Forge World consider to be worth teasing us with?  I'm going to extrapolate and suggest this this guy is going to be one of the miniatures for the Horus Heresy series, especially given the tabard and general Heresy era feel of the picture.  They've already released Angron, so could this be another primarch?  I don't think its Horus or Mortarion (they've got capes, and look different in their images in my opinion).  There's an outside chance it could be Fulgrim, but I'm not keen on that hypothesis.

So I'm going to put it out there and suggest that it COULD be Abaddon.  What do you reckon?

(image copyright Forge World).