I think it's pretty realistic to think that in a few hundred years many, if not most, people will be racially "mixed" (I hate that term because it sounds like dog breeds, personally). I actually think that the ME team did a pretty good job of including people of many racial backgrounds. Kaidan, Jacob, Vega, Traynor, and Cortez were all squadmates or very prominent crew members who clearly weren't white. Anderson, arguably the most important human after Shepard, was not white. Udina was not white. In fact, the only prominent (either major npc's or crew members) characters who seemed white were Chakwas, Joker, Miranda, Adams, and Kelly.
The one thing that I really want to see and haven't yet is a black female squadmate. That's a pretty weak demographic for Bioware. I think that Dynaheir (BG1) and now Vivienne (DA: I) are the only ones. I'm not counting the SWTOR gals (like Raina or Jaessa) because you can change their race with a customization kit.
Sidenote: I had NO idea that Kimberly Brooks was black until I read this thread. It made me go look her up on imdb and found out that she actually voiced a soldier in XCOM, which is funny because I've always thought of that voice as "the one that sounds like Ashley". Funny.