With enough luck and "accidents", will it be possible to make a fortress, where the only citizens are , well ... batmen?
(or any other non-dwarf immigrants, like humans, animal-men etc.)
Yeah, once you get your first permanent sign-up who isn't just visiting, you can end the dwarfiness if you like.
Will the game notice the difference? I realize the answer is probably no for the upcoming release, since it's a very peripheral feature and not a normal use case anyway. But this relates to the idea of the world perceiving player intentions, which is, unless I'm mistaken, the biggest purpose of fortress start scenarios.
Will those likely have the possibility to change during play? This also seems like it could related to army arc stuff once your active fort is treated more like a normal site for the purposes of wars and you (presumably, if I understand intended future design intentions correctly) can use nobles for politicking.
And not related to that, but also a start-scenario thing:
Do you have any plans yet about adding social strata beyond noble/common, such as slaves? I got to thinking of that in connection with visitors and the "Explicit standing of different citizens vs. civilization authorities" note, but it seems like it would be pretty necessary for the prison colonies in general, and could be useful depending on how fulfilling of an implementation you want with religious sites, which would arguably have hierarchy based in faith and might have relevant religious precepts, and the mining companies and military citadels which would probably be differently organized compared to the relatively anarchic situation we've got now.