I feel like senior engineers tend to focus on a specific area. How can I pick a specialization that's still relevant in 5-10 years?

• Just work on something you're passionate about. If you're legitimately passionate about a specialization go for it. If not, stick with what you're doing. Don't specialize in something to try to game the meta.
• The best way to stay relevant in 5-10 years is to take something old, tried and true, and even boring and becoming extremely good at it. When it comes to the world's most successful tech companies, they're mainly doing bread and butter stuff: Meta for example is still mainly a consumer mobile app company and mobile came out 15 years ago.
• Trying to specialize in something "cutting edge" like web3 is actually an easy way to become irrelevant. These unproven technologies are unproven for a reason: They could be dead in 5 years as people realize they weren't worth the hype.
• Software engineers do specialize as they become senior, but from my experience, they specialize more in behaviors not tech stacks. For example, a generalist Android engineer might specialize by becoming a "fixer" archetype as they become very senior, which means that they specialize in fixing very complex and deep Android bugs.

Related Q&A pair: "Does it make sense for me to choose a specialization like ML? If so, what's the impact?"