Hogwash. These are intimidation tactics by Obama's thugs. It seems to be working with one immigrant family I know who say they are voting for Obama because they fear that riots will happen if he is not reelected.
I just don't believe there will be "nationwide riots" if Obama loses. However, I would certainly like to test that proposition empirically.
The only way that anything this far fetched will happen is if after the second debate, internals has Obama behind.