I'm a little disappointed about the mini-pack, but that's life. At least we'll get the content at some point, which is always a good thing.
Regarding the soon to be destroyed races, I notice the Iconians are number 2 in the poll! Eek! Personally I love the Iconians. Not only do they look cool, but they have the interesting backstory (vs Yor). I think the races to go should be the least interesting ones, not necessarily the least playable ones. I know Brad cares a lot about the backstory - he wrote it!
The story behind the game is quite interesting, and I would prefer it to remain that way. Modders could always put the other dead races back into future games, so thats not really a top concern for me. If the story behind the game isn't good, then the races become meaningless and uninteresting. Custom races can mimic them and without personality they are quite boring.
I would prefer the Korx and the Thalans to go, but I could tolerate the Altarians being wiped out if some refugees make it to the Terran Alliance, bringing some nice tech with them and showing up from time time as special characters. I'd like to say a little about each race, and how they make me feel. I'll leave out the Terrans as they aren't up for the chop:
Altarians - There is an interesting story surrounding the Altarians and humans. Aside from that though I don't think there is any reason to have two "human" race. If the mystery becomes resolved I would be fine seeing the Altarians being destroyed, and the survivors integrating into Terran culture.
Drengin - Humanity's worst nightmare! I couldn't imagine the game without them, and the rivalry between the two is one of the defining things about the game's lore. I doubt they will go, as they are in the original backstory for the game.
Arceans - The Arceans also have a lot of history within the lore of the game. They are the first race I think of when I think "neutral". I would like to know more about their warrior culture.
Torians - These guys are too cute to die. To me they feel like Earth's best friends in the universe. The Altarians always make me think they have a hidden motive behind their actions, but these guys have a face you can trust. I enjoy the story about their enslavement and ultimate victory over the Drengin. That lore makes me care about them.
Yor - The fact that the Drengin will take these machines as their allies speaks volumes. As the only synthetic race I find them to be extremely interesting, especially when paired with the Iconians. They also look very cool.
Iconians - When I want to imagine an ancient advanced race, I think of the Iconians. They look cool, and their history with the Yor is interesting. They compliment each other nicely. The first word I think of when I see them is "sleek".
Korx - I really don't care much for the Korx. I get that they are mercenaries, but they don't feel part of the same universe as the other races. Maybe I haven't studied the lore carefully enough, but they seem like an 'extra'.
Drathi - Although this race looks cooler than the Korx, I feel about the same way about them. They seem to have a beef with the Altarians, which sucks them into the lore a little more. If the Korx were removed, and the Drathi took on a little of their persona and abilities, I think they could stay.
Thalans - I get that they come from "somewhere else", but they seem to have a seperate story, and again, this race doesn't feel like a part of the same universe as the others. It's interesting to have an insectoid race, but they don't play any differently. This is another race I wouldn't miss.
So my top choices for the chop (in order of most likely to die) would be: Korx, Thalans, Altarians and Drathi. If any of the others didn't make it I would probably shed a tear or two.