In order to make this case, what you have to do is to argue that the war was always going to be determined by industrial capacity and population. In this view, the war was not about military technique or leadership but simply about who could produce more weapons and put more soldiers on battlefields. I am not sure this argument is really true, but it can be made.
The North was vastly superior to the South in terms of population and industrial capacity. Essentially all of the factories in the country were in the North. The vast majority of the country’s railroads were in the North. The North had a much larger population, particularly when you factor in the idea that many people in the South were slaves.
From this, you can argue that the South could not possibly have won the war. The US Army was always going to be better armed and equipped. It would be able to replace men who got killed and wounded much more easily than the South could. These factors made Northern victory (in this point of view) inevitable.