Following some previous disputes about Augur reporting fees I thought that it would probably be useful to make this discussion a little bit more practical. As we know, the reporting fee is a function of 3 elements: previous reporting window fee, current REP price, and fee generating open interest. Current and target market caps are the derivatives of those. Each universe will always start with 1% fee [ref Augur whitepaper 5 Mar 2018, II.C., page 9]. Feel free to use this simulator to forecast reporting fees per window:
EDIT: I've slightly rearranged the model aiming to make it more realistic. Time horizon extended to 20 weeks. Assumptions: Open Interest - 20% weekly growth, Price - 5% weekly growth (add spikes/dips yourself).