I know I am the OP of this thread, but I never really chimed in.
I want to point out the following in the most related ETF I can think of : SLV
iShares Silver Trust (ETF)
NYSEARCA: SLV
Here are the general guidelines surrounding it:
Holdings: Physical Silver Bullion 100.00%
The Trust holds silver bullion and is designed to provide investors with a simple and cost-effective method to gain exposure to the price of silver.
http://us.ishares.com/product_info/fund/overview/SLV.htm---
Substitute the words "silver" for 'bitcoin' and you now know what this is.
If a billion dollars go into the bitcoin ETF, making that 1% of all bitcoins worth a billion, that means the total bitcoin marketcap is 100 billion if the plan is not to buy more bitcoins. However most of these ETF's are fluid, if that much money flows into it they need to make each of their shares worth 1/5 of a bitcoin. They could mean that they will be buying large amounts of Bitcoins on the open market (or dumping them if they price goes down).
there are ways (I didn't quite understand how their filing addresses this) but most ETF's allow for physical delivery. I am unsure how they plan on addressing this, if they plan on addressing it.
Another issue is the total amount of bitcoins they control, if they do not increase it, and money keeps pouring in (and they allow for physical deliver as most ETF's do) then you now will see bitcoins worth 100k each or more.
Not only are they going to be 'selling their bitcoins' to the investors , they will be making money on the transactions for life for 'managing' the fund.
You think mining fees are outrageous, these guys just made the most powerful ASIC miner in history. Every single transaction on that fund they will be making a profit from.