-costume sets
-power sets (completly new archetype?)
-missions who are more different
-"dungeons" for 8 players with arch-villains
-power-sets for the "endgame"...means more arcanate power-sets/epic-power-sets or even something total new for players who are lvl 50
-a new area to visit
So 2 things for me are important...new things for the character and then new things to do with the character.