I hope the combination of communities and revenue split will create a de facto referral program. Steemians will be inspired to recruit new users and run engaging interactive communities in their areas of specialty if the community admins can carve out a small rewards share.
I know I've been hesitant to recruit folks yet, not due to a lack of revenue split, but just due to the missing communities feature and uphill battle to retain users at the moment. As features are more robust, I think many "on the fence" people will become more vocal promoting Steemit as they feel more confident attaching their own name and brand to the recommendation. From there organic growth can skyrocket.