At worst, a patient who fails ABT’s 5-drug regimen could be retreated with an interferon/nuke-based regimen, but there will likely be other (more attractive options) too.
My point is throwing a whole basket of HCV drug classes at the virus has its downside. It's a viable strategy without a clear fallback option.
Why not treat patients initially with a nuke-based combo? If that fails try another or throw the basket at them (ABT).
Or try interferon-based therapy (good luck with that).