What domains require the least continuous learning?
If I had to answer my own question, I'd probably bet on safety critical software, but I'd like to hear what the community has to say :)
I just want to point out that COBOL developers do need to learn new stuff. There are new tools, mainframe emulators, different structures at different companies, etc.
Hardware architecture and hardware itself are the least changing parts related to software engineering. And as the result OS kernel level development and system programming don't require to relearn that often.
Is it 1 year away or 10 years away?
The business should also be super stable, slow growth, but high revenue/margins. That's probably the most important thing you should look for.
Just stay away from agencies and startups.
The churn you're alluding to happens mostly at the very thin frontier of innovation and applies largely to engineers who want to retain high compensation.
There are plenty of Java jobs though.
In the first kind of continuous learning you get more value out of your experience. In the second kind, I wouldn't say none at all, but certainly less than the first.