Warrior, Paladin, Death Knight, Keeper - 4 Plate
Hunter, Shaman, Tinker, Dragonsworn - 4 Mail
Rogue, Monk, Druid, Demon Hunter - 4 Leather
Mage,Priest, Warlock, Necromancer - 4 Cloth
Keeper - Focus on two-handed weapons, enchantments and battle spells - Regular class
Dragonsworn - Focus on Polearms and draconic powers - Hero class
Tinker - Focus on Guns, Pistols and mechanical companions - Regular class
Necromancer - Focus on Staves, Undead minions moved from Death Knight to Necromancer - Hero class
Addendum for Keepers as they are the real novelty here:
The Keeper class would essentially be a battle-mage or runemaster, clad in plate armor.
Though titanic watchers are also sometimes called keepers, these keepers are different from them in that they primarily rely on magic, like a battle-mage would.
Keeper class players though indeed have connections to Giants and runic magic bestowed upon them by the Titans.
This Keeper class fills the class niche of titanic-magic-warriors.
The main reason for Keeper title is that it fits in with more concise and short class titles like warrior, mage, druid and so on - battlemage or runemaster was kinda long :P
http://wow.gamepedia.com/Runemaster
http://wow.gamepedia.com/Rune_magic
Bards could be considered as a new Secondary Profession rather than class imho. Professions could be pepped up to convey more combat benefits in general and bards could play songs to heal, soothe, or strengthen resolve.