In my humble opinion, being monocultural as a developer is a path to obsolescence. Be T-shaped: know your specialty really well, but also a bunch of stuff more superficially.

If you have a little hands on experience with Go on top of your Java expertise, you are imo more valuable to your employer. They may even be mid transition from Java to Go, where you would be very useful indeed.

Besides, it’s just healthy to keep learning new things.

Are you only asking about the worthiness as a job skill or also for personal satisfaction?

Java will likely remain one of the common languages for the next 4 decades. Go is a better language which is why the pay rates are lower. But it is unlikely for Go to replace Java but it is actively competing against Rust to become the replacement for C.

It’s hard to predict the future, but I can point to a couple of indexes.

TIOBE measures language popularity according to a variety of factors. It has Java on a steady downward trend over the last couple of decades, but shows it as still very relevant. TIOBE does not show comparable growth for Golang. I don’t see much growth in the top 10 for languages that are especially suited to autoscaling. C# looks to be steady as a language in a similar niche as Java.

OTOH another survey from devjobsscanner that looks purely at job postings shows Java openings as very steady over the last couple of years. It also shows Java as more popular than Golang.

So I don’t know exactly what conclusion to draw from that. But learning a new language can be a helpful exercise regardless to broaden your perspective, and to keep your skills sharp.

Personally for the purpose of producing resource-efficient binaries for scaling I prefer Rust. It’s design incorporates some correct-by-construction strategies that promote high-quality code. And it’s well-suited for compiling to WASM so you can do stuff like deploy small services to Cloudflare workers for wild scaling. But I guess Rust isn’t making a big showing in the popularity charts. And Golang is popular for its lower learning curve.

RE autoscaling: effective distributed systems design isn’t really language-dependent. Java apps can scale just as well as ones written in Go. That said, I can see there being a case for Java apps not making it as easy to build that way. There’s definitely a lot of mainframe/monolith-oriented patterns in both the standard library and in enterprise Java culture.

As for the job market and career investment, I’d say this:

• Keep investing more deeply in what you’re good at. That’s your foundation and what sets you apart.
• Avoid chasing the “next big thing” based on speculation and trends alone.
• The next step in your career hinges more on your ability to think and design at higher levels than it does on lateral moves to another programming language.
• Explore languages and technology that you think are interesting, relevant, or can provide value or elevate what you’re already doing. The main benefit of doing this is to engage your brain differently and encourage change, improvement, and growth. This will indirectly improve your work and help your career.

I’ve written a lot of Java in my career and studied it in college, and I’ve written one app professionally and several hobby projects and utilities in Go. There’s a lot to like about it, regardless of its marketability on a resume.