If you stay active and do back mobility exercises and stretches every day then it is unlikely that you will end up hunched over and crippled. AS usually progresses slowly in a linear fashion whereas science, technology, and medical knowledge grow exponentially so there are lots of reasons to be optimistic that you will be able to have a normal life and a bright future. There are better medications on the horizon, as well as new and interesting research such as the human microbiome project and new developments in quantifying the impacts and mechanisms of pre/probiotics. It sounds like you have had some success in the past with dietary changes so that could also be an option. I don't have all the answers but hope you feel better soon.
