Thinking about the repercussions of the current arc, I came up with a few ideas.
First off, we have the potential to start in a world where there are no Dwarven civilizations anymore. They've all been subjugated or wiped out by others. What now?
Well, I think when starting off you have three options (other then scrapping the world and restarting the world gen).
1) Start an outpost of dwarves from a controlling civilization. You'd then get human representatives or goblin or whatnot. Changes the dynamics a little, but doable.
2) Rebellion - 7 dwarves break off from their oppressed civilization and form a new dwarven civilization. You have the disadvantage of being immediately at war with your home civilization, but probably neutral/friendly with the other civilizations nearby.
3) Dwarven settlers - If no dwarves are left at all, you could have a small dwarven group show up from overseas, or across the scorching lands of the equator. You start of neutral with everyone, I'd imagine. Although, until world diplomacy is put into place in Fortress mode, you'd probably have to have at least one of them decide they hate you, to keep the game interesting.
Side effects of this? Well, in the second two cases, you don't have a parent civilization to deal with. Which begs the question of what happens with nobles? Maybe have the original 7 be counted as nobles, with one eventually becoming King, others elevated to Baron, Tax collector, etc.
In the third scenario, you also don't get migrants from home. Perhaps both of the second two scenarios could get refugees instead of migrants, which would make for some interesting multi-cultural fortresses. The second option, of course, could allow for just Dwarven refugees joining you in your rebellion.