Agreed on the merits of the volunteer army. Conscription has always gone against my grain.
I'm not sure the draft will be necessary in the future, even if a "big war" comes up. The days of thousands of ground troops advancing on an enemy position by sheer manpower may be behind us. Knock on wood.
We were stressed on manpower with both Afghanistan and Iraq running full tilt, but I believe (no hard data) if it had only been one or the other, it may have been different. I don't know what kind of war would be "bigger" in the future, and with luck, we'll never find out.