According to leaked sources there are only three classes. My question is has zenimax commented on these classes or is it possible there are more than three classes for our nine races.

Thought there were four? DragonKnight, Templar, Sorcerer, and Nightblade.

Been Confirmed there are four. Dragonknight, Templar, Sorcerer, and Nightblade.

Likely its the case that Nightblade isn't ready to be tested yet as at PAX it was the class we heard the least about and it was not playable at the demo stations or during media hands-ons.

There's going to be 4 classes at launch, but the "classes" are not like other games... you'll be able to customize each "class" so much, that you can make something very unique to your playstyle. The class is a baseline... it's your starting point. If you decide you want to go caster heavy, you can start as a Sorcerer... but that wont stop you from using a two handed sword and heavy armor if that's what you want... You could be devoted to Tanking and still be a Sorcerer, it just may give you a specific sorcerer-esque benefit that being a Dragon Knight did not.

So four confirmed. Do you think there will be more than that?

I heard some rumours floating around that there would be 2 more in addition to the 4 they already have, I don't know for sure if this is true though.

I wish they wouldn't do classes personally but six is better than 4

From what alot fo the artles said from the press event before pax. "there were 3 playable classes but we were told there was one more called a Nightblade that was not ready yet

The classes are so open ended in this game, you pick a class for their 3 unique class trees is all.

Maybe in an Xpac

Seems like MMO developers lean towards less classes so that it is easier for them to balance the game for PvP. The more classes the more difficult the balancing job becomes so to avoid that they limit the amount of classes the game has to offer. Neverwinter a game based on D&D where classes basically define the rule set released with only 5 classes. So TESO releasing with only 4 or maybe 5 by the time they release seems the likely way they will be going to me.

Partially it is balance. Partically it is class identity. There is only so many ways to make the "sneaky guy" and the "healy guy" and the "mage guy" etc. When you open up the class system this much you really need to play to the archetypes as much as possible to give everyone a guide.