D&D Next and the thorny issue of Class

I have beenspending some time over the last month or so, particpating in the debate on the WOTC sites as to what should be in the next version of D&D. I have also been scouring the web for details (scant as they are) regarding the limited playtest that was conducted at The D&D Expereince.

Every time a new version of the game comes out the issues around class benefits often boil down to the question "Are classes necessary?" On the assumption that classes will be deemed to be necessary (and this is a fair assumption considering the desire to draw in older gamers back to the hobby), WOTC will need to work our what the essence of each class is. They want to give each class an ability or two that defines the class, and which will not be available to other classes either directly or indirectly (such as through a feat or skill choice combination). This is particularly true if they implement the proposed system that makes skills a modular optionl rule set, and allows basic play using Ability scores only.

My view is that for some classes this is easy, while for others its really difficult. What do you think are the defining characteristics for the classes set out below? You can be general or specific and please say if you think a particular class, lacks any defining ability, because then it probably shouldn't be a class at all. I have put my views in blue, do feel free to add you own in a different colour.

Cleric - Healing, Turning Undead, Limited weapon choice

Fighter - Most weapons and armour, better chance to hit and more damage

Rogue - Backstab, More access to better skills

Wizard - Pre-pared spells every day from a spell book

Sorcerer - Spells without a spell book, Spells change the sorcerer over the levels

Warlock - Pact with powerful entity grants power (could probably be a sub-class of sorcerer)

Bard - Enchantment spells and Jack of all trades

Barbarian - Rage and damage reduction, penalty for armour

Ranger - Favoured enemy, woodskills (Always worried me that the ranger kinds doesn't inhabit it own space outised of "Like Aragorn")

Paladin - Good aligned, warrior, lay on hands

Druid - Cleric with nature spells, turns into animal

Assassin - Sneaky skills allow more dangerous crits

Monk - Weaponless combat, high saves, no armour

Avenger - No really defining feature

Psion - Uses mind power instead of magic

Warlord - Fighter with organisational abilities