I don't think the map size matters too much. Nomo drew a whole continent at one point, but later said that the story will just include the places that come naturally and leave the rest out.
For me the story scale still tells much more.
Sabia wants to get revenge on her family, one of the most powerful one in the most powerful empire, and just in the last patch we've been told that her mother alone could destroy a whole town if she wanted to. Even with plans and sneak attacks this can't be easy.
And right now even if she gathered everyone she could call, Sabia most likely couldn't even handle Kira's bandit team if Neve decided to stay out of it.
As i see it, we kind of have a few "milestone" villains in the story now: Kira, then Jasmine, Lynn and finally Tyra. Sabia might not have to fight them all, or some might get grouped up, or maybe new ones could show up. A story can be written in many ways, but if Sabia isn't ready to face the weakest of the four then she can't be close to finishing the story yet either.
But that's just my guess.
