How do people end up in mainframe application development nowadays? Honest question - I’ve never seen a single post or job ad on the topic in 9 years
well i spend all my time moving people and applications off the mainframe so probably not the best person to ask, however a quick google of mainframe jobs showed up 100's (for experienced people). I have heard some large companies are instituting their own training programs for hew hires but i have no details.
COBOL (or PL/1) to any other language is a deterministic problem, imagine transpiling millions of line of code and every time you run the compiler you get slightly different output...
Anyway transpiling from one language to another ie COBOL to java is almost the easy bit, the hard bit is making the behavior and execution correct, especially when there are multiple OS and product services that don't exist outside the mainframe.
disclosure I am CTO of heirloom computing, we migrate mainframe applications to the cloud.