There are five other continents with room for a religion like SA yet I don't see anything close to SA. And by like SA, I mean a religion that actually matters. In Dwilight SA is something I hear mentioned during decision making frequently, because it matters. No where else does religion really matter like it does in Dwilight and SA dying off isn't going to make it happen for another religion.
That's not, IMO, because of anything inherent to SA. That's because it was able to develop a significant powerbase without competition due to its status as the religion of the only Dwilight starting realm to be able to spawn multiple colonies in close enough proximity to become a bloc.
Though it's also partly because many of its early members really
did care about it as a religion, and not simply as another form of power—in other words, because they were interested in the RP of it.