I think there is no way to know what is the best solution, therefore why not try some of them simultaneously.
Steam store splits into sections, where each section implements a possible solution - high fees, LLC, demos, greenlight, … In a couple of years, they could finally chose the best solution based on some indicators, such as costumer satisfaction and sales.
Naturally, there couldn’t be duplicates - your game would be either in the high fees section or at the LLC or in one of the others.
There, everybody happy.
But again, this could end up been too costly and messy.