(IMHO, it doesn’t really matter that we can’t agree on a hard definition of “old school”. It’s enough that there is something recognizable enough going on that people have put words to it.)
So, does the OSR care if it “has legs”? Clearly it has been growing of its own accord. Certainly there’s going to be a limit to how far it can grow by those methods, though.
Does it want to grow beyond those limits? Does it need to grow beyond those limits? What are the consequences if it doesn’t? What are the consequences if it does?
Perhaps, beyond the goal, it is worth putting words to what are not the goals.