Sounds like instead of 'levels' you will have to gain power by working your way up in your society.

"When you being in a secret society, you're nothing more than an initiate on the bottom of the totem pole, but as you kill monsters, finish missions, solve puzzles and explore, you'll earn access to more and more of what your particular society has to offer."

It could end up being not much different from a level based system depending on how they implement it.