If they ever add a "pure viking faction" besides the already existing Sea Raiders as bandit type, I doubt it will carry the name "Nord", becuase the Nords are already within Sturgia, according to lore, between Bannerlord and Warband the Tensions between Nords and Vaegirs within the Sturgian Principality rose so high, that they split and did fight wars with each other.
I don't recon they will add any substantially very new systems now, since we're in the Beta Phase, Beta usually means balancing stuff, fixing bugs, adding only minor things, but the groundwork is already laid, all the fundamental gameplay systems are there.
Now that doesn't mean, that they stop development with Full Release of cause they won't.
I predict, since there is so much land visible all around Calradia, that they created so much land (instead of just viewing it as a wall of fog or something) for a reason.
And since the geographical direction, in which the kingdoms are placed, are there to reflect the RL cultures and kingdoms, that inspired the Mount & Blade factions, I guess we will see at some point in the area south of the Aserai maybe one or two Sub-Saharan Africa inspired Kingdoms, one representing e.g. Mali, the other the Zulu.
In the East I could think of India- and China- and Southeast Asia-inspired factions, cool stuff could be done as special stuff like e.g. war elephants as mega mounts, that can trample enemies to death or stuff like that, but mega expensive in maintenance costs or food consumption or something.
In The North, of cause, there could be a "pure viking" faction imaginable, although you'd run the risk of creating a huge similarity to the Sturgians, so there have to be some substantial differences and in the Northeast something inspired by the Finns and other Karelian cultures.
And finally, in the west, where definitely you'd need sea travel and naval combat as new features, there could be an Anglo-Saxon and Scottish inspired kingdoms on the in Warband mentioned, but never depicted continent of Balion, where allegedly the Vlandians also come from.
According to Warband it is close enough for a regular Shipping Route existing between Calradia and Balion, atleast in the era of Warband.
And further West, if you wanna go totally wild, there could be Native American inspired kingdoms, that resemble The North American Natives, the Aztecs, Maya and Inca.
There are many ideas which could be done, to the North, East and South we already see unused land, that could be made usable by the devs (or modders, once after release modders get the tools to make a new map or modify the existing one). And as they created Calradia, they can also create Balion or a yet unnamed Jungle World and these are not the only named, but so far never seen places in M&B Lore (there is also e.g. Geroia).
But, to circle back to the origin of the thread:
If they ever add a new faction, I doubt that a Nord faction would be the first they add, since there is already Sturgia. But there are so many cultures totally unrepresented, that would give a totally new touch to Bannerlord and M&B Lore, I think, also money wise, we would see an Eastern Expansion first seeing Indian and Eastern Asian inspired factions first, since these are like over 2 billion people, if only 0,1% of them are gamers, these would still be 2 million potential customers. Sweet China money, no one can resist it.