I hear what you're saying. I'm at the age where before long I'll be an old guy. The new kids will probably think I don't know anything about some new thing X, only to find out that I helped write X.
My mother was a pioneer who helped bring major companies into the digital age. She's taught programming, database architecture, etc. and was a top ranking information systems executive for Fortune 100 companies. I learned a lot from her. It would be accurate to say she's forgotten more than most Slashdotters ever knew. That's one reason she calls me for help - because she's forgotten. The other day I mentioned a principle she taught me and she didn't know what I was talking about, having been away from it for 15 years.
The other reason she calls me is because while she could patch a Unix BINARY by manually editing the machine code, Windows 8 is a new, foreign land. She had a Vista machine before this Windows 8 laptop, but she's much more comfortable with Solaris or System 7, or any environment that runs Cobol.
I greatly respect her knowledge and experience, especially her deep understanding of timeless principles. She recognizes that today's systems and today's threats are not the same as the 8080 powered systems she wrote assembler for.
I've been programming interactive web sites since 1997. Recently my wife, who is ten years younger than I, taught me a bit about Facebook.
Each of us has strengths and weaknesses. In general, as we mature we synthesize random knowledge into principles - broadly applicable statements that reflect deeper understanding than feature X and product Y. When we're younger, we're interested in each new version of product Y, the new performance feature and this new security feature.
The foolish young person might think that the "old guy" is out of date. The wise person who has seen some things realizes that the new kid actually DOES have something we could benefit from - the PFY often knows that the virus scanner we've loved for 20 years hasn't kept up, and he knows the new, improved tools.
When I want to know relational calculus or how to bid a job without requirements, I'll ask the old guy. When I want to know how to uninvite someone from a Facebook event, I'll ask that kid over there who is building the Facebook app.