To be clear, being obsolete means that the character concept can already be represented with existing game mechanics. A character class is defined purely by its concept (the fluff), and not at by the mechanical representation of that concept (the crunch). That being said:
Druids are obsolete, because Clerics can take the Nature domain. Wardens are obsolete, for the same reason.
Paladins are obsolete, because Clerics can take the War domain.
Warlords are obsolete, because Fighters can take the Battle Master sub-class. Swashbucklers are obsolete, because Fighters already get Dexterity to damage with finesse weapons. Rangers are obsolete, because Fighters can use a bow, and take an appropriate background. Barbarians are obsolete, because Fighters can use heavy weapons, and take an appropriate background. Knights are obsolete, because Fighters can take an appropriate background. Duskblades and Swordmages are obsolete, because Fighters can take the Eldritch Knight subclass.
War Mages are obsolete, because Wizards can take damage spells. Bards are obsolete, because Wizards can take non-damaging spells, and an appropriate background.
Beguilers are obsolete, because Rogues can take the Arcane Trickster sub-class. Assassins are obsolete, because Rogues can take the Assassin sub-class.