Predicting the contents of future waves is a solid past-time of X-Wing community members (and probably any other expandable game out there). I've been pondering the unreleased factions for a while now, trying to imagine what a "core" army will look like for them. Here are my best guesses.
With the core factions, we have 1 hero, 1 siege piece, 4 trays of infantry, and 2 trays of a specialty piece (cavalry or archers). So let's fill those in for the other two factions, starting with the Latari Elves.
The Latari elves are pretty exciting. In Runewars and Rune Age, archers are their cheap, spamable units. I think it would be pretty neat to see them have 4 trays of archers and 2 trays of sword-wielding warriors. Or, instead of warriors, they could have 4 trays of archers and 2 trays of cavalry, riding those sweet Leonx beasts. It would make them feel very different, but I'm just not sure how well it balances with point costs and all that. What about the siege unit? Unfortunately, the Latari Elves never got the BattleLore treatment, so we don't have as many unit possibilities for them as we do for the other factions. But even looking at Waiqar's army, we see that FFG still wanted to make something new (the Carrion Lancer), so I think we'll see something new for the Latari as well. It could be the Forest Guardian, but I doubt that because the Forest Guardian should be HUGE. I suspect they will make some huge figures later on for the Barrow Wyrm, Forest Guardian, Chaos Lord, and something else for Daqan (maybe the Roc Warrior or Siege Golem, but since Rune Golem is a siege piece in this game, they would probably name the Siege Golem something new). And lastly, there is the hero, we only know of one hero (heroine, rather), Lana, and she rides a Leonx, so while we might see her as a "core" hero, I think it's more likely we'll see her as the first hero expansion that has a mounted and unmounted model. But then again, if my inferences about the Organized Play poster are accurate, she should be the first hero figure for the Latari.
So I predict the Latari looking something like this:
1 new hero (or
maybe
Lana on a Leonx)
1 new siege piece (maybe Forest Guardian, but probably not)
2 trays of Leonx cavalry
4 trays of Deepwood Archers
This army would be all about mobility and range control, melding two different aspects of the core set armies into something new.
Let's move on and explore the Uthuk Y'llan. I think we'll see the standard 4 trays of scythe-wielding infantry for this faction, but it's possible we'll see something more akin to the Berserkers from BattleLore (which, incidentally, are much more like the Berserkers from Rune Age than the Berserkers of Runewars). For the 2-tray slot, I'm really torn. I am a huge fan of the Viper Legion from BattleLore, but Flesh Rippers have always been a huge component of the Uthuk Y'llan armies. I think that shooting vipers from bows is probably a little too cartoony for what FFG is trying to do with this game, so I suspect we'll see Flesh Rippers as cavalry units. I think it would be neat if they went back to the original Runewars from some of the design on the Flesh Rippers. They were a little more skeletal and less muscular, making them look more other-worldly and demonic to me. I would love to see them combine the aesthetics of the BattleLore and Runewars Flesh Rippers. For the siege unit, the Chaos Lord is the obvious choice, but as with the Forest Guardian, I think it would make for a good huge piece later on in the game's life. In the mean time, I would like to see something reminiscent of the Doombringer (burrowing demon beetle) or the two-tailed scorpion that Malaana rode in BattleLore: Command. The lore has mentioned from time to time that the Uthuk Y'llan inhabit a scorpion-infested wasteland, so I would love to see giant scorpions become a thing for this faction. The problem with this is that Waiqar is already using a worm for the siege piece, so using an insect or scorpion for the Uthuk may make the factions feel too similar. In that case, I think it might be neat to see something inspired by the Chaos Lord, but save the Chaos Lord for later. For the hero, I'm 100% convinced it will be Ravos.
So the Uthuk "core" army could look something like this:
1 Ravos the Everhungry
1 new siege piece (hopefully some demon-arthropod monstrosity)
2 trays of Flesh Ripper cavalry
4 trays of Berserker/Blood Harvester infantry
This army is basically the evil mirror of the Daqan, but we can expect a lot of self-sacrifice in this faction, which will make it feel different. Additionally, I'm hoping for poison abilities either through the siege piece or through Viper Legioin archers in the future.