So what's next?
Well, we are beginning to see glasses that run apps, wrist wear that monitors your fitness and your communications, and drones and robots that individuals can own. These are still infant technologies, with lots of runway.
More broadly, finding a way to intelligently and easily monitor the physical things around you remains a challenge. This business, often called "the Internet of Things," is well underway, but still too much of a kludge.
The biggest screen of all, the television, remains low-hanging fruit. So-called "smart TVs" still aren't very smart. And a no-brainer TV that needs none of the myriad of boxes sold today for streaming content, yet has a unified interface with standard programming, still hasn't caught fire.
There are huge business opportunities in things like foldable screens; radically revised batteries that hardly ever need recharging; and 3-D printing for consumers that is simpler, and yet more practical.
Health is another big opportunity. In 2014, the tens of millions of diabetics in the U.S. shouldn't have to draw blood to check their glucose levels, but they do. Noninvasive blood and tissue analysis, easily used by normal patients, could work with other diseases as well, saving both lives and money.
Finally, we have to get a handle on security and privacy. Passwords don't work, and reliable biometrics everyone can use are just starting.
I don't know what else will be common when CNBC is 50, but I am confident that the ingenuity of designers, dreamers and engineers will make 2039 as unrecognizable to its audience then as 1989 seems today.
Walt Mossberg is the co-executive editor of the tech website Re/code, and co-executive producer of the country's most prestigious technology event, the Code Conference. For 22 years, he wrote the Personal Technology column in The Wall Street Journal, and was co-founder of All Things Digital. NBC, the parent company of CNBC, is a minority investor in Revere Digital, the parent company of Re/code, and is an operating partner of Re/code.