ARC is probably going to remain viable insofar as pure damage output is concerned. Jobs aren't meant to wholly replace classes, but supplement them with a new set of skills and specializations. A BRD's damage ceiling will, by nature of the job, likely be lower than a pure ARC's due to the necessity of balancing support skills and damage skills.

Nothing is dying, and ARC will likely receive a pure damage job (ranger or sniper) when the second round of jobs is released.