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.
04/01 - Mindless Self Indulgence
04/05 - Kataklysm
05/10 - Mastodon/Gojira
05/12 - Down