Technology will always move forward. No matter what stack or technique you are using at the moment will probably be replaced with another one soon. Therefore we must not stop learning, especially the special skills below that will never be outdated to be used as a software engineer.

Math & Logic

It's true that you don't really have to be good at math to survive in the world of programming, but at the lowest level, we'll always need math, at least in the logic part. Besides, we know that sometimes we just can't avoid using combinations, recursions, permutations, etc. So it never goes out of style.

Algorithms

Creating step-by-step procedures for desired goals and then executing it is an essential skill for fellow developers. Over time, you will face various cases that must be resolved. Therefore, continuing to practice algorithmic skills will go a long way toward solving more complex things.

Problem Solving

The key to a programmer's job is to solve problems. You shouldn't raise other issues, such as bugs, when solving one. So the expertise to find the most efficient way of dealing with problems has always been a very important skill in this subject.

Debugging

It's hard to have zero bugs when developing software, this makes debugging is important. Ability to locate the bugs, reproduce it in development-mode, and find a solution to handle the bugs will always be needed, regardless of the tech stack that you currently use.

Learn New Language

Even though there are many programming languages ​​around, the concept will always be the same: as a tool of communication. Therefore, the ability to learn a new language is an important skill that must be possessed. With this, you can switch to any programming language easily.

Conclusion

You can use any stack or language to code, but don't forget to remember to practice and improve the skills above. This will help you regardless of the technology you are currently using.