Regarding price setting, it turns out that the Chicago Board of Exchange is using the price on the Gemini exchange for their futures contracts:
https://fortune.com/2017/12/12/winklevoss-twins-bitcoin-futures/The Winklevoss twins are co-founders of the Gemini exchange, which Cboe Global Markets Inc. is using as the basis for the daily settlement for the bitcoin futures that began trading this week.
If a whole eco-system is built up which uses Gemini for price-setting, they'll eventually get their ETF approved, also using Gemini for the price.