I liked 4E 3 Tiers of Heroic, Paragon and Epic, but I don't think Epic really needs to be part of the core rule. 20 levels are plenty, and very few campaigns will make it beyond there, so "EPic" will rarely see deep support. It happened neither in 3E, where Epic Levels were pretty much a broken concept (well, IMO), nor in 4E, where it was core and pretty much worked mechanically. Groups fall apart and interest in the same same campaigns wanes too quickly to really have much of a chance to get to Epic.