It is a hard swallow to assume all of them would follow suit, considering the implications. They would much more likely provide both options, and of course that makes room for the v-pak (no one analyzing future revenues for either company was excluding this) claiming a minority of the market with an inferior product.
At worst Sovaldi and Harvoni prices will come down a bit across the board. Personally I have a one year target of $120 for GILD.
But what you have presented in your post is exactly the reasoning many have for selling and/or waiting to enter a position. I don't find this to be justified by anything other than fear, which has some justification of course. But it looks like the panic/over-generalizations are mostly over. Jmho
GL and happy holidays.