Ask HN: How do you know when it's time to drop your specialty?
Case in point: I was once the "OS/2 goddess." I taught classes in operating systems internals, I wrote books about how to use it, I was OS/2 network administrator for the electric company, I was a lead perpetrator in the user group community.
But when OS/2 went away, so did my career. I didn't want to admit it; after all, I was comfortable with that technology; I had great contacts and it was easy to do what I needed to; and I loved doing it.
However, at some point, there's a "come to Jesus" moment. You tell yourself, "It's been a good run, but now it's time to move on." In my case, it was when I realized I was getting gigs where I was paid to remove OS/2 from a business, not install or maintain it.
...And then you have to think about what to do _instead_, and the lessons you should take away ("I'm not going to hitch my career again to any company's single product").
Sometimes the path is an obvious one (if you can write about one technical topic, you have enough cred to write about another). Sometimes, not so much.
What caused you to recognize "I need to change my specialty" and how did you decide what to do next?