Ferrus: We know Ferrus will be there. That is almost 100% certain. Update - He will be there!
Kor Phaeron and Erebus: This will be the other character series models that I reckon will be there. With the pics of Kor almost finished in White Dwarf a month ago (which would have been taken sometime before that) I would say there is a 70% chance of them being there. Update - They will be there!
This brings us to 2 Boxes of the character collection. So I really really think that will be it. No 2nd Primarch this year at Gamesday. When you take into account Simon Egan putting his talented fingers to Ferrus since JulyI don't think he would have had time to do 2. The only other sculptor in the Heresy series so far is Edgar Skomoroski who is doing Erebus and Kor Phaeron, and rumour has it will be doing Lorgar.
If anyone might pick up another character it may be Steve Whitehead (of Palatine blade fame), but I would not be sure what or who. Same with Keith Robertson (Phoenix Guard) who is also exceptional.
At this point I would like to say: Throne. . . Forge World your sculptors are all awesome.
Circle of Ashes: Word Bearers Destroyer squad will be there in my opinion, having seen it in progress at the Weekender 90%. Update - will be there!
Kharybdis: gorgeous drop pod. Centrepiece of awesomeness. This will look amazing on the Isstvan 5 board. 80%
Vindicator: still new on the picture circuits I would say 60%. Update - will be there!
Karcophoni: More EC! 60%. Update - will be there!
Space Marine Fortification tile: Blake has been working on it since June I think judging by its standard at the Horus Heresy Weekender. I would bet it is there. And on the big board too!
Now for the outsiders.
Typhon: I reckon Typhon has a shock appearance chance of being there. This is to patch the absence of any love for the Death Guard Characters in the Series so far - this may be early sculpt stage
Emperors Children Command: Emperors children Captain and Standard Bearer (as they get so much love anyway why not).
Khärn: Working progress.
Fire Drakes: Work in progress.
Cityscape tiles x2: I also think there is a chance of 2 new Cityscape tiles that Blake has found time to do (or more Mortalis).
Mortarion: For a Halloween release. I think that would be lovely shock.
Massacre Characters: Lucius, Vairosean, Mor, Wayland, Kor Phaeron, Erebus, Sevatar, Mawdrym, Numeon, Heka'tan, Khärn and Delvarus. And obviously the Primarchs.
This is all from my own opinion and is just Wishful thinking. I don't deal with hearsay and gossip etc just observations, previews etc. The great thing about FW is they don't show the Primarch's til they are actually complete. But still show the fans enough to keep them happy and excited about the future of the Heresy.
Thanks to them all.