Quartz has a summary of a study that examines the salaries offered for programming jobs, broken down by language requirement. Click bait? Maybe, but it is certainly some interesting data.
They also quote the following advice taken from some discussion of the results:
Though a language currently in high demand … might get you the best salary, it might … peter off over time. It’s better is to focus on being well rounded, with a firm grasp of algorithms, design principles, and the ability to pick up new languages and concepts rapidly.
Let’s not kid ourselves: it will peter out over time.