The Farmville stop was on the old N & W mainline between Petersburg and Roanoke. That line is now a very nice bike trail - and NS is using another route between Petersburg & Roanoke - I think it was part of the original "Virginian Railway" Right of way.
As far as I can tell the proposal that I have seen uses all ex-NW trackage, whether it takes off from Richmond or Petersburg. The latter will require the construction of another connecting track at Collier.
Now if it is going to avoid Lynchburg and go straight to Roanoke then it could use the ex Virginian trackage from Abilene Connection west. The Virginian trackage east of there has been abandoned long time back. But I suspect that they will not bypass Lynchburg on that route should it come to pass. Of course getting this service to use the Kemper St. station in Lynchburg will require some weird backup moves too.