I must agree with Zooloflyer completely!
As much as I enjoy A320Riders unstoppable pessimism, I believe that there will always be companies out there that values personal maturity a great deal. It will be more important that you have the right attitude and will be a low risk pilot to train rather than the idea that you will be there for 40 years.
About your flight training, let me put it like this, I have not once looked back on my flight training with regret, and I was out of the cockpit for three years. Since you get to do this with little or no financial risk I would say that it would be foolish not to pursue this path. Most pilots will tell you the same. I believe that with your realistic outlook it will be very rewarding for you.
About your flight training facility, If I would get my flight training at FSI paid for by the GI bill I would be there yesterday! They are one of the most professional training institutions in the world!
About your age. I don't know too much about the situation in the states, I do know however that two of my friends over there just got hired at the tender age of 34 and 36. One of them went to AirTran after a few years at TSA and the other to FedEx.
To start flight training can be a hard decision to make, but you seem to have the right attitude and insight, I would say that you should go with your gut feeling. If you don't you will probably end up thinking of the things that could have been.
All the best to you.