Human Dwarf (including duergar and muls) Eladrin (including drow) Elf Half-elf Halfling Gnome Half-orc Orc (if half-orcs are allowed, why not full-blooded orcs?) Shadar-Kai Tuathan (come on, make'em a race)
Different races:
Genasi Changling Goliath Githzerai Githyanki (sauce for the goose) Shifters, at least 3 varieties
Human, Halfling (the true, hobbit-y ones, give Dragonlance back the Kender), Dwarf, Elf, Eladrin (perhaps fold them back into the Elf and make their abilities baseline modular), Half-elf, Gnome (make them the Rock Gnome again instead of the weird mini-Eladrin), Half-Orc, Dragonborn, and Tiefling. Essentially, if it is in a PHB1, it should be in the PHB of DDN. If people want to take something out, they can take it out themselves, the designers should accomodate ALL versions of D&D 1E-4E, just like they claimed they are going to.
So... Human Dwarf Elf Eladrin (maybe, could be folded into the elf, IMO) Half-Elf Halfling (hobbit-type, Kender belong in Dragonlance) Gnome (Rock Gnome, please!) Half-Orc Dragonborn Tiefling
Stuff like the Kender-esque halfling should be a modular thing included in Dragonlance, as should the Tinker Gnome, and the Minotaur. Stuff like the Warforged, Changeling, and Kalashtar should be in the Eberron book. Thri-kreen, Muls, and Half-Giants should be in Dark Sun. Drow should be a modular version of the Elf (as should Eladrin, IMO), perhaps even in the monster book. Sverfneblin could also be in there with them. Derro too. Perhaps all the dark versions of races could be in the MM or DMG, but I wouldn't mind seeing them as modular versions actually in the PHB.
Under the idea of unifying DandD players, I'd vote for including all the races from the core edition books. If it has been in any PHB, then include it. For my part, they could morph some together like High Elves and Eladrin to keep the number down.
The ideal for me answer is in the core world would be . . .
Humans
The most common species with enough advantages some one would want to play them.
Dwarves
Got to have them. It isn't core DandD without them.
Which isn't to say, every world needs them. I ran a DandD world that was African based, and there were no Dwarfs. Turns out they are canibals in African mythology. I replace them with Motia. The elves became souless imortals with a weakness to iron. There were no gnomes either, but there was a winged race of monkeys. So I had my anti Tolkien period too.
Elves
Yes, and eventually in all there various flavors from the core books.
Halflings
Yes.
Gnomes Yes . . .But I'm not sure which niche they fill that Dwarfs and Halflings don't. They are a part of my home brew world, and I've come up with uses for them.
Half-elves Yes . . .iconic now.
Half-orcs
Yes . . .iconic now. Once they were as heritical as Tieflings. Something to keep in mind as we debate changes. Yesterdays blasphamey is todays icon.
Eladrin (1)
Only if they are made High Elves. They certainly are very Fey like and magical. Should be good for any fantasy world.
Dragonborn
Yes . . I can see people have grown attached to this race. We need to admit they are cool. I would give them a different name, but they fit well enough.
Tieflings (2)
No . . This is a personal preference. Their race history is awefully specific. I think the core world needs to be an every world, which means it will be a bit generic If you can call a world with Elves, Dwarvs, and Dragon Born generic.
Talking about this with my son yesterday, he very easily included them in my home brew world. "Dad, just make them Drow and lop off the tail." This would work, as they are 'victims' of an ancient pact.
Shifters
No . . not in the core world.
Changelings
No . . personally not a fan of making monsters part of the core world. I can see where one might want them or any other race in a world, but not for the core universal world. Though really they would probably be a type of elf or fey. Hey, are you putting the White Wolf world in my D and D? Will we get to play vampires or wizards. Wait we do play wizard. (Joking)
Goliaths
No . . Good for a speciality world, but not the core world. I assume we are talking some type of giant.
Thank you for your efforts Kingreaper. I appreciate your posts.
Humans Elves Eladrin (I'm a fan of keeping the split in what was defined as "elf" in earlier editions) Dwarves Halflings Dragonborn Tieflings Half-elves Half-orcs
I'd like the D&D Next Monster Manual to also contain a section like in the 4E MM that gives basic rules for playing humanoid monsters as characters. In that they should include:
The PHB1 races should be fairly comprehensive and give us more than 1 splatpage for each. Give us culture and attitudes without necessarily giving us too much specific campaign stuff. The MM should be reorganized to not just be alphabetical, but organized around humanoid encounters vs. wilderness/wild/magical monsters.
I'm a fan of players able to play 'dark' races and 'monster' races and I think most players expect those two options. Therefore the first list of player-character races should include a few of the most classic of DnD 'monster' races. (Classic races: Against the Giants, for example)
In this fashion the rules address a very common player request and would suggest how to handle it story wise/world flavor.
Humans ( With some options for variation ) Elf ( With options for variation to include Eladrin as High Elves ) Dwarf Halfling Gnome Half Elf ( or an option for a race to have 'Elf Blood' as a theme ), Half Orc ( or an option for a race to have 'Orc Blood' as a theme ) Dragonborn Teiflings as a Human subtype ( possibly a 'Fiendish Blood' theme ).
Oh, and plenty of options in the DMs book and/or monster book to support playing pretty much anything in the monster books with Sentience ( Yes, i know its a bad definition, but you know what i mean).
Will we get to play vampires or wizards. Wait we do play wizard. (Joking) 
