Very interesting ideas. Perhaps 3 boxed sets: Heroic, Paragon, Epic? I always found lvls 1-3 far too limiting. The 1-10 level range may turn out to be sufficient for quite a number of gamers, and you could put all the basic types of adventuring (dungeoneering, urban, wilderness) in the first set. Set two could then include mass combat (PC's can start leading armies), dominion rules, running a country etc. Set 3 could then focus on planar adventuring (something which I always thought fitted better with very high level PCs).
And another stray thought about the more complex classes - perhaps these could be in the Paragon set as a kind of prestige classes/next step up. The basic set would give the typical archetypes, while becoming a ranger, paladin, assassin etc. would only be possible from lvl 11 onward. The first ten levels would be 'basic training', and specialization is only possible (and not mandatory, of course) in the next tier...
And another stray thought about the more complex classes - perhaps these could be in the Paragon set as a kind of prestige classes/next step up. The basic set would give the typical archetypes, while becoming a ranger, paladin, assassin etc. would only be possible from lvl 11 onward. The first ten levels would be 'basic training', and specialization is only possible (and not mandatory, of course) in the next tier...