Hello, Wilhelm:
Do I stand a chance of keeping some ROM at least for a few years?
It all depends upon Your behavior, rather, that behavior which dictates the aggressiveness of AS: There are certainly things we can do to accelerate this disease and absolutely other/opposite things we can do that will have the reverse effect.
In fact, the stage before actual fusion is called 'fibrosis' (and it limits ROM as a 'preview' of what will someday become permanent skeletal damage) and Professor Ebringer suggested, through proper treatment (and this is mostly SELF-treatment through dietary methods), we could turn the clock back about two years. Of course by the time I heard this I needed TWENTY years taken off, but it is a personal decision others have now that I regret not having.
HEALTH,
John