I don't think it's as big of a deal as people are making it. Futures are cash settled, not bitcoin settled. I understand that the owners of the futures contracts are "incentivized" to make it expire within the range of the contract they own, but people forget that futures contracts are a two way street. If manipulation of the bitcoin market is due to futures, it really depends on who has more money to move the market, the buyer or seller of a futures contract. Neither wants to lose money.

Side note: The price of futures DO NOT determine the spot price of its underlying asset.