Well we know the Paragon Tier will be giving you Paragon Paths and that the Epic Tier will be giving you Epic Destinies. But I think some concepts might be similar, but yet more suited for the Heroic Tier. But I don't think that it should work exactly like Paragon Paths or Epic Destinies. Some such concepts might fit into base classes, either as a new class to it's self or as part of one or more others, but I think others, particularly the Ur'Priest and Blighter would be more "open", so an Ur'Priest could have Wizard, Sorceror, Psion, ect. levels, but also be an Ur'Priest. Here's how I think it should be done: these should be feats, like the Class Training Feats, which give you appropriate abilities and such, but there's no actual class.