There’s a stereotypical view of job opportunities for older workers, and it’s not pretty. It goes something like this. If you’re past 50 and thinking of a career switch, forget it. The opportunities for older workers in the new economy are pretty much nonexistent. And you’re in even worse shape if you’re in your 50s or 60s and retired but want to get back into the workforce in a job that is both challenging and financially rewarding. The only spots available are low-skilled and low-paying—whether that’s burger flipper, Wal-Mart greeter or Uber driver. Boy, have a lot of people have...