To be honest, late game sucks as of recent. There isn't anything to really do except level up and grow bigger. Maybe add a new location or a boss, or at least make the enemies grow according to the player's stats, because nothing about late game is noticeable right now.
A macro late game would be neat. You gain access to a new area filled with other gigantic characters so you feel small again. Macro dungeons, quests, mini games,etc.
Some quests could involve going back to the starting area and it would be jarring to be so huge again. Kind of like big and little world from super Mario 64.