Binance could trade ENIGMA too. Way better than this etherdelta.

True. According to the white paper,  listing new assets on the platform should also bring considerable profits. As a "brokerage" in crypto world, there is always a positive expectation as long as the exchange size expand.  

Just a simple calculation. the profit of binance in a quarter could be estimate in this formula, if considering exchange is the dominant income: P = mean(Volume(day))*0.001*90.  Volume(day) today from coinmarketcap is $ 72,330,737. Assuming this is the mean Volume each day. Thus, the P is $6,509,766 in total. 20 % of P is $1,301,953. BNB price today is $1.3. If taken this price as the mean(BNB) each day, it is likely to be 1 million BNB in all to buy back in this quarter(seriously I bet it is around 0.5-2 million BNB). There is 100 million BNB to be burnt. It might take much longer time than we have estimated. What confused me is that the profit of Binance shouldn't be just BNB(at least right now). So do they really need to buy back BNB, or just let 20% BNB in their profit burnt, which may not influence the market at all?  In conclusion, I was too optimism about their buy back speed. Really hope my estimate is totally underestimated their burning speed. Let's wait and see their performance in 5 days.