I’ve started career in a startup which was an official ibm partner. I’ve little bit exposure into ibm I series , rpgle , db2 and COBOL.
The math looks good on paper, but $2/line code translation ignores the 'Engineering Gap.' You can't just move a 30-year-old RPG/COBOL system to Postgres on Cloud and expect the same results. AWS RDS gives you a 99.99% SLA (52 mins downtime/yr), but these AS/400 'tanks' regularly hit 10 years of continuous uptime.