I think the Bitcoin ETF and Bitcoin Future are no different, both of them are the vehicles of the popes to deceive/manipulate bitcoin prices as happened in the middle of December 2017.
There is actually a significant difference in use case and potential impact on the market.
The futures as we know them right now are nothing more than empty products meant to provide legal exposure to those willing to bet on an increase or decrease at the end of the contract date. It's all cash settled and there is no way these products contribute to Bitcoin in any shape or form. On top of that, you can basically short an unlimited amount of Bitcoins as long as you have enough cash.
ETF's that are backed by actual coins provide legal exposure that is generally more focused on the long term, and with that we can expect coins to remain out of circulation for as long as these shares aren't liquidated back to fiat. The more demand there is for coin back ETF's, the more custodial entities need to stock up on Bitcoin to keep up with the demand. There can't be more ETF shares than there are Bitcoins in circulation.