That there are opportunities does not mean you can get a job. That your friend got an As/400 job does not mean you will get a job.
On the other hand, if you transit to other fields such as Java, but with a strong background of AS boxes, you will have more opportunites. IT professionals should always be ready to learn new technologies until they quit.
Indeed, Java was overheated last year. In any case, Java has a very strong industry momentum and it can offer people more opportunites.