I won't happen next month, but I am definitely waiting for the moment Wall Street is making it possible to trade Bitcoin like you can do with stocks. That would be an insane announcement. It will most likely take some years before it's possible. I have patience.

You mean like buying and selling it on an exchange? We already have that. Buying bitcoin is better than buying something that represents bitcoin and I don't think Wall Street is going to think up something better.
most public exchanges(coinbase, bitfinex, bitstamp) are consumer level exchanges.. where any deposits over $10,000 get flagged, delayed and questioned. and most regular users of those exchanges are holders of sub 100 bitcoins. most of the time sub 5btc..
but the winklevi ETF would be on much a bigger scale..
firstly brokers will be buying bitcoins in bundles of 2000 coins. (far bigger than consumer exchanges allow). and with wall street regulations and insurance. we will see investors throwing millions of dollars at the ETF, not thousands at consumer level exchanges.