So I turned 55 years old last Monday, am employed as a senior software engineer for a startup in the voter education and civic engagement space, and I guess I'm qualified to comment on this. I read this same refrain over and over, and if I peer just a little bit between the lines I think I perceive a common pattern. A lot of these people are just not up to keeping up. Learning the next thing is a wearisome burden for many of them. If you get to that point in your career, then yes, that's pretty much death in this business. If you haven't moved into management by that point consider another line of work.
For my own part, this is still what I love to do. I'm busy 10 or more hours a day and at least eight of them are spent with some technology I knew nothing about six months ago. I was layed off from another startup at the end of September and started this current gig three weeks later. We just finished five weeks ramping up on Google Container Engine, during which time I also learned to use GNU make for the first time, and learned about etcd and Google Compute Engine. What it boils down to is this: stay interested, and stay current, and you stay employed. If those things are not within your power you no longer belong in this craft.
For my own part, this is still what I love to do. I'm busy 10 or more hours a day and at least eight of them are spent with some technology I knew nothing about six months ago. I was layed off from another startup at the end of September and started this current gig three weeks later. We just finished five weeks ramping up on Google Container Engine, during which time I also learned to use GNU make for the first time, and learned about etcd and Google Compute Engine. What it boils down to is this: stay interested, and stay current, and you stay employed. If those things are not within your power you no longer belong in this craft.