I have only heard lvl 30 on reddit a while back. Not sure if that's true tho.. I've only reached level 20 thanks to cheats however since I wanted to see how the gear progression looked like.
About end game I'm also curious.. I hated the fact that the first game became so empty when the game was "finished". No enemy respawned and zones were completely dead. Hope there's something recurring in the game world other than arenas (which I hope are repeatable...)
