According to Karune the Firebat will no longer be trained at the Barracks. In Starcraft 2, Firebats will be trainable through the Factory building, becoming a Tier 2 unit.
Karune: In terms of ‘realism,’ the Firebat has a much larger mechanical frame (with increased hit points), thus would need a larger facility to deploy these units. Additionally, the Barracks currently already has several units available to it, including the Marine, Medic, Reaper, and Ghost. Having the Firebat at the Factory also helps to make sure it is a Tier 2 unit, since its added hit points makes it quite the adversary on the battlefield.