Protease inhibitors are very expensive. Telaprevir and boceprevir each is estimated in the tens of thousands of dollars per treatment course and most estimates are up around $70,000. Add to that a cure rate of 75% to 80% for naive patients with non-resistant HCV strains and you still have a need for a cure for hundreds of thousand sof patients.
So, even if protease inhibitors become part of the treatment and cure, there will be plenty of room for a HCV-Cide just as a matter of cost.