I started as a C++ dev and have found my way to Typescript + React. Lots of jobs available, including remote work. Honestly at the senior level I expect less focus on specific tech and more focus on directing overall architecture.
The big technologies I see our company struggling to hire are your big data engineers. Scala, R are big in that space. But I'm not sure how easy it is to break in without a degree in data engineering specifically, since the real money is in parsing the data intelligently.
If you don't want to completely pivot, dev ops tools are a great thing to add on. Everyone wants a Kubernetes cluster and no one wants to maintain them.
And there is always the path of management, but people are worse to work with than products, IMO. :)
