It's a big world out there. Would you ever imagine that D would be taking market share from... Extended Pascal? But there's a naval architect who designs great big ships with a 500k sloc codebase he is exploring porting to D. Web guys get the attention but enterprise users are a much bigger world than just that.
If something is growing very quickly then saying it hasn't yet dethroned C, so it won't ever be significant seems to me to be a bit brittle thinking. Compound growth and the passage of time - thats what has been underway for some time now.