Hey, we deemed this list "ways to stop an asteroid" -- we didn't say it couldn't be Earth!
If none of the nine aforementioned asteroid deflection methods pan out, there may not be much else to do if a near-Earth asteroid's course can't be altered with decades or even centuries of advance warning. So we may need to fall back on panicking.
You know... chaotic exoduses from major population centers, food hoarding and manic attempts to break through the gates into underground government bunkers. Plan to spend any time of the roads? Brush up on "The Road Warrior," and if you plan on surviving make sure a few viewings of "Mad Max" are under your belt.
If the future's really bleak, leave a friendly note for the cockroaches -- or whatever you think the forces of nature will pick as the next dominant species on Earth.