With the appearance of this (which aparently everybody knew but me):

We can try a more serious speculation about which minors will be in, guessing from their location in the map (take into account that it is a game in progress and some factions could be emergent/conquered/displaced, but there are a lot of single-region factions remaining so we can assume that most of them are the original. (Also, its an event-demo, so it could be scripted for the AI to be peaceful, you know the care companies these days put in the info fans can get from their screenshots).
So let's give it a try (I repost my map just for convenicne, for those who want to compare.
So far I'd say that:
HISPANIA:
- Rome has most of it, but there are 4 free provinces and all of them are independent factions. For the placement they could be (from north to south) Gallaeci, Lusitani, Celtici and Turdetani.
AFRICA:
- There are a lot of factions that I don't know where they came from (most of them occupying territory that we know belongs to Carthage. I think that we can expect both Gaetulians and Garamantes
- In Lybia there are 3 different factions, that I'm guessing are three Lybian nomad tribes (i only know the Nassamontes), although one could be a conquered Egyptian region. Cyrenaica is conquered by Rome, I'd say there is a strong chance it starts as an independent faction.
- There are 5 other factions that make me doubt. I guess Numidia and Mauretania are almost confirmed provided they are not being cheap on the number of factions, I don't know what's that on Carthage, it's not roman and it's definatelly not Carthaginian white, could it be an emergent Carthaginian faction? (maybe a family?)
BRITAIN:
- No surprises here. Iceni, Brigantes, Picts, probably Dumnoni and in Wales Silures/Demetae/Ordovices. I guess it's nice to confirm that Ireland gets its own faction (i feared since the province -Caledonia and Hibernia- hinted a single faction). So yeah, Hibernians (Eblani) seem to be in.
GERMANIA AND EASTERN EUROPE:
- I'm (gladly) surprised to see that most, if not all, of the factions here are single-region factions. Again, I'm happy CA has not gonne cheap on the faction count. I'm not gonna list them all, so i guess you can consider all the factions i put in those regions as strong candidates to be in.
- I guess the biggest news here is that Dacia seems to be splited in three independent regions, that could open the door to Getae, Moesians, etc.
- Also, the Kingdom of Dardania and the Scordisci could both be there =)
GREECE:
- If you look at the left image, you see that Macedonia has lost Larissa and Pella, and that the colors of those regions don't match with any of the seen in the right image, so it could be emergent greek factions.
ASIA MINOR:
- Not entirelly sure here. So far I guess we can confirm independent Pergamon and Galatia. I don't know what are those 2-3 factions between them (the light blue screen in the first screen and the green and brown in the second). Also Armenia seems to be the dark-green one, one of the very few multi-region factions i have seen besides Rome and Seleucia.
ARABIA:
- I'm amazed at the number of independent tribes in Arabia, the Levant and south of Egypt. I'm not even going to try to list them. I don't think i could even find the names.
EAST:
- It seems that Bactria (blue), the dahae and the Chorasmians are there, along with a lot of different Scythian tribes. No Mauryans tho. Btw, what are those 2 provinces south of Bactria? I doubt they create Baktria without Baktra in it. Could it be that Bactria is the tiny red one and Transogdiana has a different kingdom in it? Maybe its an emergent faction.
- Oh btw, the Bosphoran Kingdom is there too.
Well, you guys go into details ^^ I have to leave for now.