The IPO dumping of funds already negatively affected BTC. The effect will be isolated to ETH, in which the IPO investors will be just a tad bitter.
There was a fair amount of XBT selling by the IPO that coincided with the bottom in XBT/USD. This is nothing more than classic "weak hand" selling of XBT.
If loads of IPO buyers sell when it launches will they hold their bitcoins or sell them?