I think it depends what kind of venues they're pulling for. If they're playing the same size venues as 2012 then I don't see Fear Factory being unable to pull in people as a headliner. I mean DevilDriver headlined this year and FF is a lot more popular than DD.
09/19 - Crowbar/Revocation
10/06 - The Black Dahlia Murder
10/14 - Machine Head/Children of Bodom
11/30 - Slipknot/Korn
12/27 - Protest the Hero