My guestimate is a little less then rkrw's with the caveat that it will likely be improved upon. As Thomas has pointed out INFORM results could give us a good hint at that. I would think Ribavirin may be around in the first go-round of an all oral regimen (in at least the non-responders).
Now if we say it happens in 4-6 years and even if you one assumes VRTX is one of the companies (but not the only; obviously I hope Roche/ITMN/VRUS is one) then one has to question the valuation for Vertex. Yes if they are alone perhaps even a higher valuation is warranted. But my opinion is that Telaprevir is far from the ideal Polymerase in this type of scenario especially if one believes (like I do) that treatment duration will be longer then that being investigated in the combos with PEG/Riba (I would guess 24 weeks and maybe even longer for an all oral regimen).