Given that those stuck on JDK6 tend to be large corporations with deep pockets (and often a policy requirement to have a commercial support contract for all their software anyway), I think that's precisely the part they wouldn't want to do for free.

Our use case is a proprietary app that still requires Java 6. Fortunately, OpenJDK 6 is still supported and security-fixed (well, backported patches) in Debian/Ubuntu.

OpenJDK 6 won't be around forever. I strongly advise figuring out an exit strategy for that app.

well, yes :-) It's an old version of Quova, an IP geolocator from Neustar. The new version is way better, but we can't be bothered rewriting the stuff that uses it until we have to.

Java 6 EOL should be your "have to". It will be easier to fix before you get a hard deadline, and it's easier to upgrade by one version twice than by two versions once.

Having been in environments that still needed to support JRE6 and be secure, the support contract from Oracle is actually not horribly priced and is actively fixing CVE's that are not available to the public.