How about an example? Present a short COBOL program that is actually more concise than a (say) Java program? The example presented in this blog article seems a likely candidate, and yet would be much shorter in modern languages.

If you want to make the case that COBOL is still a good DSL for its niche (report generation?), it seems like there should be some straightforward examples. This is super easy to do with the aforementioned SQL or Matlab.