(Image from Privateer Press' website)
There’s nothing like the long wait between and announcement of a new edition, and the long gap until getting it, or at least getting enough new info to talk more about it. I placed my order for the new preview battlegroups... but they mention they are just now starting to ship them, so who knows how long until mine arrive.
Privateer Press released their most recent Primecast+ yesterday, with renders of new Khador models (they look great!), and released an article about the process they use when making resin models, and safety tips. People interested in this game have probably already seen those though.
Since I have some time before new stuff arrives at my doorstep, a fun way to spend the time might be to look at what armies will be legal in the Prime format. We know that every current army will get at least one (and likely two) Prime legal armies in time, and we did receive some information as to what some of those would be, but with a lack of other things to talk about for the moment, let's take a look at each faction, and come up with some ideas.
I am basing my guesses on a few factors. Things that are iconic for a faction, armies with new releases, and which themes PP has already mentioned. I also think the warjacks and warbeasts will have to exist in more than one army, because I do not think there are enough unique jacks to create significant disparate groupings of warjacks. To me, this lowers the chance of seeing jack or warbeast focused armies (except in some cases, like the mini-factions).
Circle Orboros
I feel like the way armies are being split now, the Mercenary/Minion focused themes aren't making the transition as is (although, we'll have to see how they implement Mercenaries and Minions in MKIV before we'll know for sure). The most iconic and unique themes in Circle are probably Devourer's Host (Tharn) and Bones of Orboros (Wolds), and Devourer's Host, I believe, has the most recent set of new releases. So my guess for Prime-legal armies: Tharn and Wolds.
Convergence of Cyriss
We have heard from both the August Primecast and from various posts on social media that the various mini-factions should be completely Prime Legal. Convergence is the biggest of these mini-factions, but I don't think it is unreasonable we do see all of it make the jump. I suspect that the Strange Bedfellows theme will not be playable in any form, so my guess for Convergence: Vectors and Infantry armies (essentially the Destruction Initiative and Clockwork Legions themes, as they are).
Crucible Guard
Again, they have mentioned that all of the mini-factions would be prime legal. I suspect we'll see Crucible Guard just receive a single army containing the entire faction (so basically, what Magnum Opus is right now).
Cryx
I think Dark Host (Banes) and Scourge of the Broken Coast (Satyxis/Scharde/Black Ogrun) will be our Prime-legal choices. They have released a Bane army as a preview demo army, and I think it's both thematic and iconic, so I think it's likely a Prime choice. I don't think there are enough jacks that aren't in the Bane army to make for an interesting jack army, meaning the remaining choice is between Scourge and Ghost Fleet. Both feel iconic and distinct, but Scourge has recent-ish (2018) new releases, and I don't think they want a potentially heavy incorporeal army starting out in Prime.
Cygnar
Clearly, they are releasing the Storm Legion this year, which will be a purely MKIV army. I think this probably eliminates Storm Division as a Prime-legal army. They hint (or outright say) that Gravediggers (Trenchers) will be Prime-legal. So what does that leave? Heavy Metal is too jack focused, and I think those are out. So that leaves Sons of the Tempest or Flames in the Darkness... hmm. Flames has recent releases, which makes it appealing as a choice, but I'm actually going to go with Sons of the Tempest (Gun Mages) here, because it is purely Cygnar, and significantly more iconic for Cygnar as a whole. So my guesses: Gravediggers (Trenchers) and Sons of the Tempest (Gun Mages).
Grymkin
Again, we're told that the whole faction is making the transition to Prime. I suspect that we get a single army, including everything in the faction, because I don't think an infantry/beast split into two armies really creates two interesting choices.
Infernals
Our final mini-faction. Everything is in Prime, and I'm guessing they just get the one army, which is all of the Infernal models, and ignore Hearts of Darkness for purposes of MKIV.
Khador
Winter Korps is one of the early MKIV releases, so I don't see Winter Guard making the jump to prime. Privateer Press has also mentioned that Man-O-War would be a Prime legal army. So what would be a likely second legacy army? I think Flame in the Darkness and Warriors of the Old Faith are probably on the outside looking in, although I think both have merit as being Prime legal armies. I think their warjack-focused army (Jaws of the Wolf) is out, because they will need the jacks elsewhere. That leaves Legion of Steel (Iron Fang) and Wolves of Winter (Doom Reavers and Greylords), both of which feel possible. I'll lean slightly towards Legion of Steel. They feel more focused thematically, and they provide a very different look to anything else that would be Prime Legal, so I think they are a good choice.
Legion of Everblight
I think Primal Terrors (Blighted Ogrun) are a shoe-in, given the recent-ish releases, and self-contained theme. Using all of my guesses from above, I think we can assume Oracles of Annihilation will be out, because of the Minions. Ravens of War doesn't feel terribly cohesive to me, so I think we are going to see Children of the Dragon (Nyss), which also have the benefit of including the Virtues, another recent Legion release.
Mercenaries
Privateer Press did give us some information here in the recent Primecast. Rhul, Cephalyx, and Pirates will have Prime legal armies. What about the other themes? I actually think Flames in the Darkness has a shot here- because we don't care about the origin Factions anymore, I think they'll move everything into a Flames in the Darkness Army (and give it the Mercenary Faction, because why not?). There are lot of recent releases, and they can keep it pretty tight and interesting. The other themes don't feel like locks to me, so I think that is all we'll see.
Minions
I believe they have mentioned that Farrow and Gators would have prime legal armies, and I don't think we'll see anything more than that. Will Work for Food feels too general, and Vengeance of Dhunia feels like it'd be more likely a Trollblood army.
Protectorate of Menoth
We have received the beta rules for an Exemplar force, and I think that sticks into Prime. For a second army, I cannot see Creator's Might (warjacks) for reasons stated above. Guardians of the Temple (Flameguard) has potential, but instead I'm going to guess that we will see Faithful Masses (Paladins + the random faithful). I think this has the benefit of covering a lot of random models, and may actually be representative of what the Protectorate's remaining forces look like (whereas I think the Flameguard fought the Exemplars and lost).
Retribution of Scyrah
Well, they aren't going to be around in MKIV anymore (replaced by Dusk), so Retribution shows an interesting case- any Prime armies here won't be replaced by new armies, but instead, just rotated out someday. Kind of a sad ending for the Iosans.
For MKIV armies, I think we get the Legions of Dawn (Dawnguard). They are still active in the background, with Vyros founding a colony north of Rhul, if I remember the IKRPG background correctly. They are probably a shadow of themselves, but they do have a cohesive self-contained army. My second guess would be Defenders of Ios. These again, I think, are at least partially active in the current world (as part of the previously mentioned colony), but they've also received a few new releases (the House Ellowuyr models), which would make them appealing to keep active.
Skorne
My guess here is Exalted (Immortals) and Masters of War (Cataphracts and Praetorians). I am tempted to just have Cataphracts be the army, but they don't have enough choices to be on their own, really, and I think even though there are enough Praetorians to be their own army, they just aren't visually interesting enough on their own to be the choice. Immortals have had recent releases, and have a Battle Engine PP would be happy to sell more of, so I think they are definitely in.
Trollbloods
I think Storm of the North is a shoe-in, given that they had a full release a few years back, and were designed to work together and be a distinct force. I also think Champions are a fairly iconic Trollblood unit, and you need at least one theme that includes them.
For my second guess, I'd guess Kriel Company, as this catches many of the other models, gives a good mix of infantry units, and plays and looks very different from Storm of the North.
Anyway, eventually we will know for certain what the plan is, but I think these are pretty good guesses. I'd love to hear your thoughts, especially if you disagree!