Thank you for the heads up! If we happen to miss this timeline, what would be the upgrade pathway for already certified Java 6 developers? Would it be for Java 14/15? Or, we would have to take a fresh certification?
Also, what would the suggested alternative to this exam?
Yes, a fresh certification. Your next step after that date would be to take the 819 (non-upgrade version of the Java 11 cert)
Note that Java 14/15 are not LTS (long term support versions) and therefore don't have a cert that goes with them. That's why the exam skipped from Java 8 to 11. While nothing has been announced yet, I would expect the next new cert to be for Java 17.