That is hard to difficult to predict since so much of what makes a codebase/framework/tool stick is somewhat arbitrary. You can look for industries that move sl

That is hard to difficult to predict since so much of what makes a codebase/framework/tool stick is somewhat arbitrary. You can look for industries that move slower which basically means web development is probably out. The linux kernel is probably going to be around for a quite a long while so maybe that's an option. I might suggest however that the focus on long lasting codebases is perhaps misplaced. You can't predict that very well. But you can help a codebase stay relevant if you get to know it deeply. Perhaps you should instead look for the project that looks interesting and relevant to you and perhaps your work to understand and develop that codebase will help it stay relevant for 20 years.