We will be getting procedural beast race civilizations at some point, but I kind of doubt we'll be getting any new stock races on top of that. From what Toady has said in the DFtalks etc he doesn't seem too keen on adding any more of them, that's how I'm interpreting this quote anyway (bolded part in particular):
But there are a lot of interesting questions like that ... it happens any time we have a new mechanic that's related to one of the main creatures we have to go through and ask ourselves five different times what does it do, and we aren't interested, really, in building up our stock universe, but we figure we have five different groups ... they're not incredibly diverse, they're somewhat diverse ... and then as we start adding in things like ant-men, like all the animal peoples are starting to get their own civilizations now.
Capntastic: Yeah I've noticed that.
Toady: Especially in this version that's coming up; they're actually going to have them. Because back in 2D you had bat-men riding giant bats and they had blowguns made out of cave spider legs that they shot cave spider chitin - or whatever it's called, darts - through that were poisoned with cave spider venom and so on. So they had a civilization up to the point where they were building objects and they'll have that again for the next release. Then that leads to the question, what are the ethics of a bat-man. We know a lot about Batman's ethics I guess from reading the comic books and stuff but then there's ant-men; what are their ethics? What are the ethics of lizard-men? Are they all the same? And so on. We have all these non-inventive animal peoples races but it should allow us to explore some new ground anyway, especially in terms of geographic determinism, in terms of the different environments they have should change their civilizations a lot. So it's going to be interesting to go through; I don't know what happens when a lizard-man starts drinking.
Threetoe: Okay, this next question is from James, he asks 'Will you ever begin to include randomized main races, or will the player interactable races always be limited to token dwarves, elves, goblins and humans? And a smattering of chimera tribes' ... the animal people.
Toady: Is that what he means by the smattering of ... I don't know how to say these words, is it chimera? Yeah, it must be the animal people. Unless you meant something else.
Threetoe: Yeah, we could always just call the animal people something else, other than turtle man, we could make it some other name and still be a turtle man.
Toady: I think it's always been in the plan to have randomized main races, it was up on the old dev pages, I don't remember if it made it anywhere on the new dev pages or not? I think it might actually be there. Maybe not. It would be the last one, because doing randomized civilizations is an extra step beyond randomized monsters. Because we've kind of been easing in, we have the forgotten beasts now, we've got the titans, those are randomized. We have some of the underworld creatures randomized and we wanted to ease in to having some of the regular kind of monsters in the woods and stuff, randomizing those with a few extra night creature entries at some point and then kind of ease in to having some randomized regular creatures and then finally adding in randomized civilization creatures. The problem with randomized civilization creatures is there needs to be a lot of exposition or you're just going to be completely confused about what's going on, but it would definitely be an option, I think there would be a slider or something for how strange you want your world to be because we definitely think having dwarves and elves and goblins is cool for a lot of people just to kind of understand what's going on without having to do a lot of extra reading.
Taking all that into account and also the fact that we will be having parts of the current races/civs splinter off and form their own groups at some point, possibly even including changes to their appearance, there wouldn't really be that much point to adding new standard races as well. Not to mention when all that is done creating your own custom civ through modding should be easy.