You are all comparing D3 with D2 with expansions because everybody is so damn sure that D3 gets an expansion with some extra classes.
Market segments do have to do with archtypes, it's just not a direct link. As I said before there are multiple segments, in this case the segment of the rpg gamers which Blizzard targets with D3 can be further seperated in a lot of ways. Medieval rpg gamers, modern rpg gamers, mmorpg games etc.
Archtypes is a way to separate the medieval rpg gamers even more.
And I know what I'm talking about, you simply don't understand them. Game design goes hand in hand with marketing, cause the game is designed in a way so that certain people will buy it.
Now if you think I'm some troll I'm not, I'm enrolled at: http://www.stenden.com/nl/studies/bachelor/MEM/Pages/default.aspx might wanna grab google translate.
Also the warrior archtype is covered with the barbarian, cause the archtype is a melee fighter. The Barbarian covers both 2H, Dual Wield and Shield.
The Archtype is not a fullplate wearing guy. It's just common with the warrior archtype. They play the same, just different art.
Why does everybody think that D3 will have an expansion with new classes.
I never heard Blizzard say: we will make an expansion with extra classes.
That's just everybody thinks because they refer to D2. But this isn't D2, it's D3 so stop using D2 in your arguments and what not.
Also (@ Pryda), all arch types will be covered if you look at it from a marketing perspective.
Their are multiple segments in the RPG market, people that like melee combat, people that like ranged combat and people that like magical combat. (To keep it simple.)
When there is a game where you can choose a class, these three arch types will be covered.
Why? Because it would be a slap in the face for any company to ignore a segment they try to target. Blizzards target for D3 are people that play RPG style games (mainly) but also older players that know D2 and D1 or other franchises.
It comes down to this: if they do not include the ranged combat arch type they will have a segment that would not buy their game (a good part of the segment might still buy it, but sales are reduced no doubt).
This is basic management and economy.
Biggest reason that the 5th class will be a ranged character. (The base product will want to get most segments. The strategy to put it in an expansion is possible but the sales will not be as high as if it was in the base product.)
Also my poor English might have screwed with the sentences.