I think a physically backed bitcoin ETF will be huge for the price short and longer term. I am basing that opinion off of what happened to the price of gold after physically backed ETFs were introduced. It likely will bring in so much demand that it can't help but spill over into the spot markets as well.
Gold went up roughly 6X after gold ETFs were introduced, though likely all of that increase was not due to ETFs.
Some good info in here about it:
https://steemit.com/bitcoin/@jrcornel/new-bitcoin-etf-application-may-actually-gain-approval