I read a small article from Willy Sansen, titled ‘Solid-state circuits and a career for life’ from 
ISSC Magazine.
He came up with a question – What advice can be given to students who want to build up a career in solid-state circuits? Then, he left four pieces of advice. I copied those advices in this post for my sake, however, will be more glad if you also enjoy the reading.
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- To be successful in a career, maintain a very specific field of expertise. Too often a designer runs through many designs, to find himself in a corner where he knows a little bit about everything. He must, instead, strive to be number one in the world in a specific field of expertise as if it were a hobby, to keep himself wanted on the market.
- Be known as an expert. Present papers at conferences or workshops, or publish papers or abstracts. Nobody is an expert unless he is accepted as an expert.
- Become an expert on an international level. The time is gone when an expert could be an expert in his little corner; globalization has flattened this world. The competition may be close by, but could also be on the other side of the earth. The designer must thus be accepted by experts everywhere.
- Give presentations to colleagues, to your boss, to students. Transferring knowledge from one person to another is an art. Only by doing so regularly, can a designer be efficient in making clear why he is an expert.
“
I do like the sentence “Transferring knowledge from one person to another is an art”. Yes, be an expert, be willing to share, and try to teach others in a good manner.
EveryNano Counts 
Advice #1 and #2 are valid for an academic career where you need to build a name, not for an industrial one where you need to keep your value in $$$. Following the first 2 advices in the industry will lead you with 100% probability to lay-off at some point in time. Flexibility and cross-disciplinary understanding of issues is key in the industry.
I agree that flexibility is important in Industry because it is money driven. However, I do feel being a expert in some special field is equally important, or even more import! For me, flexibility is easy, meaning that you can be easily replaced. If you are a real expert, you will always be needed in somewhere on this planet, unless your discipline is totally useless for others, which is rare.