COBOL work doesn't actually pay well compared to other languages, and it isn't that bigger market. Why? If your business logic and requirements haven't changed, why change a running system? Even if you could transpile with 100% accuracy, then you'd lose speed. Maybe you've gained an operational advantage, but there are other ways to do that. On the other extreme, you need to modernize badly, and so a rewrite is actually feasible because you can take advantage of new technologies, especially web and mobile. Between those use-cases, middleware exists which does allow you to bolt on even more awfulness. Finally, businesses die or get acquired. Sometimes good stuff is lost, but equally bad or old stuff is purged.

Maybe ironically, that Emscripten URL won't load for me.