You will be able to decrypt a file produced by age. All the cryptography there is standard, you'll have a compatible library in whatever language you'll use in

You will be able to decrypt a file produced by age. All the cryptography there is standard, you'll have a compatible library in whatever language you'll use in 20 years, if you think the first party Go and Rust implementations won't survive. Using common libraries, I can create a python program to decrypt a file produced by age in a few hours, I think.