You'd want to look for technologies that were used 20 years ago, that we're still using today. Chances are high that they'll survive the next 20 years. Things

You'd want to look for technologies that were used 20 years ago, that we're still using today. Chances are high that they'll survive the next 20 years. Things like HTTP, JavaScript, C, C++, Python, Java are all still in regular use now, and will likely still be used 20 years from now.