Let's see.
In 20 years your field might have made large parts of my field redundant. I truly hope so :-)
Programming is still a young profession and it's growing at a tremendous pace. The population pyramid of Programmers' Land actually looks like a pyramid which might cause programmers to think that older people can't make it.
I know many older folks in IT who are still active. My old man continued until he was 70. They may not know the newest tricks in node.js or machine learning but they are the only ones who know the old legacy code that lock-in users and protect their jobs.
I bet you and most of your colleagues will be active until retirement. Just like lawyers may continue as partners (partially or mostly doing managing or marketing) many programmers might transfer to management.
A lot of programmers have long formal education but the market for programmers without education is still huge and the salaries for programmers without formal training easily beat almost any other professions where there are no educational requirements and a lot of professions with educational requirements. In which other profession can you realistically hope to start with salaries of 60-80k after a few months of online courses?