Isn't Archbishop Lefevbre's line the uninterrupted line of succession? The Church does exist intact, but not concilliarly - isn't that the point?
Unfortunately, the society bishops don't possess ordinary jurisdiction, so they can't be considered to the apostolic hierarchy. They are material successors of the apostles, since they are validly ordained bishops, but they lack jurisdiction, which is the authority needed to carry out the Church's mission to teach and govern.