I'd be surprised if they didn't release a brd or some other music based class by the first expansion, and they definitely should. However, I'm doubtful they release it at release, although that'd be a nice surprise. I'm fine with this though. I hope they release the game with the classes already announced and maybe one other mage or utility class. By releasing with fewer jobs as they did in FFXI they can more accurately gauge if the mechanics of the game are working as intended.
I try to be a class half-full type of guy; at least we can work on our physical level and subjob/2ndary skills prior to the release of classes: Brds, dancers, pet classes, support, etc. And by time these jobs come out, which I'm willing to bet heavily they would, we'll be better prepared.
All that being said. I really enjoyed brd. I got it 69, and it was going to be my 3rd job to 75. However, I retired from FF before that point. I did always love how useful I felt on brd though: unique support, debuffs, and an excellent puller. Also, it had one of the more interesting story lines in terms of job progression compared to other jobs I tried and equally loved: Thf and Nin.