Ask HN: How to remain employable till 60 as a software developer

I am software developer having 6 years of professional experience. Professionally I have created small 2d games in c# and c++ for appstore and playstore all these years.I want to increase my chances of being employable in software industry till 60.What kind of learnings I can pursue right now ? I am planning following : 1] Implement most of the Data Structures and algorithms which are generally asked in interview and apply them in work if possible. 2] Learn a functional language.I am gravitated towards haskell. 3] Learn TDD on my side projects. 4] Be an open source contributor so that there can be a chance to grow a career in that project. How you guys find this plan ? and what you guys are doing to make sure you remain employable ?