However like any CDN content, the goal would be for it to be cached if it's in common use across AMP sites. One JS module that covers a large number of content

However like any CDN content, the goal would be for it to be cached if it's in common use across AMP sites. One JS module that covers a large number of content delivery sites seems like a plus to me. I can't vouch for the whole concept yet though, still reading through their spec.