The shipment of coal is the only bright spot for the RR's right now. All other commodities are down by large percentages, trailers and containers down about 9%, wood and wood products down near 20%, scrap metals down around 30% and automobiles/auto parts down around 30%.
As factories are shuttered, people loose jobs and can't pay high electric bills, and more homes are unoccupied due to foreclosure, electric power use will decrease with less coal used. I would not expect much more than 2 or 3% drop in coal carloads as recession proceeds. Only thing that can significantly reduce coal carloadings (and coal use) is converting coal to syngas for piping to power plants or converting to renewable fuels. Adding nukes would not decrease coal use for at least 8 years.
Positive effect in fewer carloadings is most Amtrak trains across the US now are running on time - a first for many years. Fewer cars means fewer trains, but also layoffs for the RR's.