Tony's lymphona was uncontrollable, but even had it not happened I agree they maybe should have had everything finalized and set in stone before announcing it. Rumors leaking out and speculation is one thing, but to confirm it before everything is set in stone doesn't seem all that responsible.
08/08 - Slipknot/Lamb of God
09/30 - Revocation
10/04 - The Black Dahlia Murder
11/12 - Kataklysm