I can only speak for the java environments, but the concepts apply potentially everywhere. Keep your knowledge fresh. I've seen lots of people still sticking to old technologies like
EJB and
JSP and having no clue on stuff like Spring Boot, REST API's, microservices etc. Learn concurrent programming, become a guru in performance, dig deep and understand concepts like aspects, proxies, go in depth of how ORM works, when it acquires and releases connections, the different transaction isolation levels. Go further and understand distributed systems, service oriented architectures, eventual consistency, messaging. Also, work on your skills: how quick are you able to work? Is your code easily readable and maintainable? Are you able to design tests that efficiently catch regressions? Are your integration tests reliable enough to go and push the code in production?
That, mixed with some talent, will make you a really hot senior dev. And, once you get proficient also on operations (aws, docker, kubernetes, nginx, security, linux...), you might even try and go for higher positions than developer.
And don't underestimate Ritchie's suggestion, it's a very powerful method
