Ribavirin is a nucleoside analogue. It stimulates the T cells in the body to fight the virus.
Interferon attacks the virus by interfering with its ability to copy itself and spread throughout the body. Interferons are proteins produced by the cells of the immune system that prevent viral replication.
So the MO for the HCV SOC is, in layman's terms, stimulate the immune system to fight the virus and inhibit the virus's ability to replicate itself. Kill what is there and keep it from growing.
And the last I checked, PSI-7997 was a nucleotide polymerase inhibitor, and PSI-938 is a nucleotide analog polymerase inhibitor... again the idea is to prevent viral replication.
HCV is hard to treat because it mutates. To prevent mutation, you have to kill the virus quickly. No matter how much you inhibit viral replication, proper treatment for HCV will likely always include something that boosts the immune system.
Therefore, I am open to correction here... but that said, I don't see Ribavirin going away in the near future.