My post is predicated under the assumption that the volume of futures trading will be larger than the volume of BTC exchange trading someday in the future. This assumption makes it slightly more likely that a futures market has the ability to influence exchange rates due to margin.
Two examples: 1) trading in a futures market and 2) trading on an exchange
Ex 1. If a futures contract begins to go negative, the contract holder must either decide to 1) close out at a loss or 2) add more cash to the account in order to satisfy margin account requirements. With this is mind, all futures holders would have to decide which option to choose. This decision could create the possibility of momentum if the exchange rate were to change.
Ex. 2 When trading on an exchange, the holder doesnt have to make these types of decisions at one time. Rather, a holder can decide when to buy or when to sell their position.
From a futures market standpoint, a lot of trading involves stop loss and TA strategies. This also happens to some extent in exchange trading. This creates a large pool of participants in both markets that behave in accordance to expectations of how others in the market are (and newcomers will also) behave. With the large plethora of TA information bought and sold between companies, this creates the expectation of price movement. The results of this are often additional futures purchasing and exchange rate fluctuations that either precede or follow actual decisioning made by participants.
From an exchange standpoint, the interaction with futures markets enable arbitrage opportunities. Since participants in these markets do not behave in a solo manner (only futures or only exchanges), this creates opportunity to buy on one platform and sell through the other. The net of this behavior keeps futures markets and exchanges tied together closely.
At least with respect to present day currency futures and exchanges, there is a general relationship between volume of futures trading and exchange prices. This doesnt suggest causation, but it does suggest a strong correlation. Another way put, if BTC prices on the exchange are highly volatile, we might see a huge increase in futures trading because of the speculation interest. More futures trading, more price volatility on the exchanges.
In conclusion:
1) Futures markets and exchange market participants have different decisioning that influences market behavior and price
2) Futures markets may significantly alter BTC exchange rates for as long as futures trading volume is higher than exchange trading volume.
3) Over time, the futures markets and BTC exchanges will become more intertwined resulting in less volatility between the platforms
Final comment: Once the futures markets open, price volatility will stay rather consistent and will correlate positively with good news and upbeat market sentiment. As these interactions between futures markets and exchanges mature (also as BTC availability decreases), volatility will decrease.