If a person is deemed cured (SVR = undetectable at treatment end plus 6 months), how could the virus have more of a chance to rebound based on the precise treatment protocol that got the immune system to SVR in the first place? In other words, if you are undetectable at 6 months post-treatment, the overwhelming odds are that you will never be positive for that particular HCV genotype again.
My whole point is that for non-ifn treatments the immune system was NOT put into hyperdrive so there will be more cases of the immune system not fully controlling the disease and leaving control entirely to the drugs - which are then stopped.