[bribriagain]

1. A WMD attack on a U.S. metro area

That's your call 2. WMD attacks become routine in the U.S.

see no. 1 3. U.S. civilization is destroyed

? 4. The human race self-immolates

?

[Man of the Right]

I don't think it will be 8 billion years, which is when the sun is expected to consume the earth.