I think that the 10-20% death rate is more of a worst case scenario. On the other hand, I wonder what the world population difference is now compared to back in 1918. That alone will drive up the raw numbers quite a bit, even if this flu remains mostly mild. Just looked it up-1918 population was 1.8 Billion, 2009 population is 6.78 Billion. Thinking of it that way, preparing mass graves in case of a worse case scenario is good thinking. I'd hate it if my loved ones couldn't be buried due to lack of preparation-we know we are in a pandemic, we don't know if it will come back more severely in the next year or two-no one knows, but we do know that it sure as heck could. It would be foolish NOT to prepare. Don't you think the people in charge would be raked over the coals if the situation worsened and there was no where to put the dead bodies. I'd be ticked.
It was a 10 to 20% death rate with people who had the flu. Overall it was 2-3% of the world's population.