According to Norbert Bischopberger, Sofosbuvir does not need to be supplanted by a better nuke, and the answer for genotype-3 could be adding a drug that is neither a nuke nor an NS5A. (Bischopberger rules out adding GS-5885, which has weak activity against genotype-3.)
This is precisely the line we should expect from GILD's Chief Scientific Officer, no? ; )
So, sounds like there is still clearly an opportunity for a better 2nd gen NS5A or perhaps non-nuke or PI that shows activity against GT3 (not sure which ones currently in the clinic do; I know simeprevir doesn't work on GT3). Also, sounds like less of an opportunity for a 2nd gen nuke if we are to believe the GILD CSO, but there may be a shot given that the follow-on nukes might be ready for the market around the same time of the follow-on drugs from other classes that could be potent against GT3.