It takes an average of 10–15 weeks working full-time to become a junior developer in a new programming language.
We all have a limited time in life, a better use of your time will be to learn the programming language that’s replacing COBOL. Maybe be it’s C# or Java 🤔
Studying COBOL might get you a temporary job but so will any of the more popular languages. Picking one of those will open the doors of opportunity where COBOL will lock you into a specific area.
Unemployment is high but if you have the same 10–15 weeks available, thinking long term may be a better idea.