I don't know all the classess in D&D, but I sure would make a healer and a tank. Those are usually the hardest to find in a group and if there is more options there maybe be more played. I would love to see a swordmage if I am correct it can be a tank? I would play that in a heart beat.
Swordmage is a defender, yes, and basically the most "pure" one. I think it's going to be put in the game quite soon, since it's one of the staple builds in FR.
Dilige, et quod vis fac (Love, and do what you will)
With paladin/ranger being most likely. I don't believe 4e had a necromancer type of class, which is what I would have preferred, but the game is going to need something for the darker sorts. And wow never did have a necromancer class, despite it's popularity back in the diablo days... neverwinter could cash in.