The Winklevoss Bitcoin Investment Trust is sponsoring an ETF. Very good lawyer they have: http://www.bloomberg.com/news/2014-08-15/spiderwoman-brings-hope-to-winklevoss-twins-bitcoin-etf.html
As Wachtwoordt once said of the SEC, I don't think they can stop it, but they can surely delay it.
The amount of liquidity which will then become available to flow into bitcoin is essentially unlimited. It's a hole big enough to drain the whole ocean through it.
My best estimate of a desirable target date for the issuers (assuming SEC does not seek to delay it unreasonably) is November 8th, 2014, which is the 10th anniversary of the issuance of GLD. I do not have expert data required to form a mechanism-based timing estimate.
While COIN is the best, because it is NASDAQ, you can be assured that if it tarries, a London, Frankfurt, Singapore, and/or Hong Kong listing will occur before 2016. Any of those would suffice to drain a lesser ocean. A Japanese listing seems likely to take longer.
Once COIN does the heavy lifting, we'll see a flood of clones and mutants lining up to compete.
And then the real fun begins:

