The most traditional and/or classical racial archetype not yet treated in 4E? IMHO, it's the Shapeshifter/"Changeling", who will imminently be represented by Doppelgangers (themselves modelled upon a race actually called "Changelings" in 3.5E, moreso than traditional Doppelgangers) if not in the
Eberron Player's Guide, then in
Player's Handbook 3 I imagine.
Goblinoids would be nice too. In fact, several of the traditional "monster" races might be cool, although some would certainly be redundant with other races: Orcs, Hobgoblins/Bugbears, Goblins, Kobolds, Medusae, and possibly Centaurs or Satyrs. Furries... I don't like; I'll watch Care Bears when I wanna see anthropomorphs everywhere.
In 4E, we've pruned elves down into three distinct races, and no more. However, if there's one more traditional D&D race that hasn't been mentioned yet, it's one final elf-type: Sea-Elves. Trouble is that you've gotta be playing an underwater/ocean campaign for them to be meaningful, and then you've got to include Merfolk and Sahaguin, too.