Looking at the plotlines post that @raddu wrote, and specially to the new options added on the FB group, it seems pretty clear that the designers intention was to move the setting from a Cold War status to a World War scenario.
The Tyr Region has been in this Cold War status since Kalak death, but then it has started to move very fast to a complete chaos: several SKs are dead, the Dragon is dead, revolts have started on several CS, Dregoth is back, etc.
And then we have all this “new” players:
The Kreen Empire is planning an invasion of the Tyr Region
The Dead Lands powers, with their own problems with the undead bugs, are also starting to look at the North
Nature-masters (and benders) coming back and forcing halflings to take part on world events
I don’t think the designers had something planned, but it really seems they were moving to this war scenario.
So, the questions: how do you think it would happen? which power groups would form an alliance? will someone win or would it mean the destruction of the existing civilization?
Given that there are 3 kreen nations plus the big “Empire” they are a contender. But then with the Dead Lands there are just so many undead and they don’t have to eat or deal with supply lines, so they’re a contender. But neither of them have 3-6 Sorcerer-Kings (+2 if you count the north). Fun to think about.
To make interesting a global war scenario what would be needed is to have different motives to fight and different opportunities to make new alliances (and betray them).
I wouldn’t have the three kreen nations united to the Empire. In that way, the players will have open the opportunity to gain them as allies using diplomacy.
Regarding the Dead Lands, I think that they are at fight with a force of undead bugs from the south. What if this bugs are provided and pushed by the Kreen Empire? Then the motive for the Empire to fight would be to gain new undead recruits, but they will be also at war with the kreen if they know that.
And last, it would be easy to have the different city-states taking different approaches. Tyr and Balic would probably fight. But Urik, Draj and Raam will be more reluctant, seeing the war as something still to far to them. Gulg and Nibenay will be in the middle, as always, and maybe forced to be allies at some point. The northern ones are two more possibilities for diplomacy.
And then you can have Dregoth trying to make an alliance with the Dead Lands, to have Giustenal as an “independent kingdom”.
SK can take care of the Dead that leaves the Deadlands. Although, it would cost them a lot more resources in order to take them out within their domain, as there is not much to defile in the DeadLands to pull energy from.
If the SK face the Dead Lands army united, probably yes.
However, I don’t think it would be easy given the enormous numbers of undead that they can mobilize. And on each battle they can also replenish their rows with the recently dead.
But in the end is more a narrative decision than any other thing. If you want to have this war scenario, you can easily justify it.