From EN World: What We Know About “D&D Next”:
The goal at the moment is to include all the classes that were in the first PH style book for each edition.
Surely someone else has already compiled this list, but since I didn’t find it, I compiled it myself.
Note that many classes appeared first in a supplement for a previous edition. I’m not listing the first appearance of each class. I’m listing its first appearance in Men & Magic or a Players Handbook (first PHB for editions with multiple PHBs).
In the non-advanced line, you had race-classes and the Mystic. Race-classes aren’t included because it seems that D&D next isn’t going that direction. The Mystic, rightly or wrongly, I’m counting as Monk.
AD&D2e had the “specialist wizard” & “specialist priest” which I am also omitting from this list.
- Assassin (1e PHB)
- Barbarian (3e PHB)
- Bard (2e PHB; optional 1e PHB)
- Cleric (0e Men & Magic)
- Druid (1e PHB)
- Fighting-man/Fighter (0e Men & Magic)
- Illusionist (1e PHB)
- Magic-user/Mage/Wizard (0e Men & Magic)
- Monk (1e PHB)
- Paladin (1e PHB)
- Ranger (1e PHB)
- Sorcerer (3e PHB)
- Thief/Rogue (1e PHB; the Holmes Basic Set)
- Warlock (4e PHB)
- Warlord (4e PHB)
For a grand total of 15 classes. Though I think there is the possibility of some of them being combined.
Note that a Psion class was also mentioned in the D&D Experience seminars.
Here they are in roughly chronological order...
- Cleric (0e Men & Magic)
- Fighting-man/Fighter (0e Men & Magic)
- Magic-user/Mage/Wizard (0e Men & Magic)
- Thief/Rogue (1e PHB; the Holmes Basic Set)
- Assassin (1e PHB)
- Druid (1e PHB)
- Illusionist (1e PHB)
- Monk (1e PHB)
- Paladin (1e PHB)
- Ranger (1e PHB)
- Bard (2e PHB; optional 1e PHB)
- Barbarian (3e PHB)
- Sorcerer (3e PHB)
- Warlock (4e PHB)
- Warlord (4e PHB)