If too much of the stover is consumed in the production of fuel, the ability of fields to produce corn would be degraded significantly. This would significantly reduce the sustainability of stover as a feed stock. Of course the advantage of cellulosic ethanol is that it can be produced from a wide variety of organic matter including many plants that can readily grow on land that isn't suitable for growing food crops. Even with those kinds of inputs, however, the world's rate of energy consumption growth is not indefinitely sustainable based on fuels of this type and reductions will be needed.
[Source: American Society of Agronomy]