Corinnguard
Hero
They could be reintroduced for 5e/5.5e. But would they be introduced as they were in earlier editions of D&D, or could they be reintroduced in a new format such as a feat chain? If brought back as they were in 2e/3e, then you would have to deal with the drawbacks that come with multiclassing. As for the feat chain, it's something that's being used by Level Up to get that Prestige class-like feel.WotC needs to stop jerking around and reintroduce Prestige Classes.
Of course, it would be easier to bring back the Prestige classes as subclasses for a given class.