I'd be curious to know whether there's a good way to avoid this. As someone who's currently in high school and looking to major in CS, this really worries me - am I actually going to be able to find a job a few years from now? Should I be planning to study something else instead?

Personal opinion, the general guidance I give to teenaged kids of friends:

The best way is to choose to do it because it actually interests you, not just because you want the money. You can get a job with the degree despite the glut of graduates. Just accept that you may not always be getting the $150k/year starting salaries you sometimes hear about.

But if CS is only of passing interest and you have other majors you're considering:

I wish more people would minor in CS, rather than major in it (NB: Not all schools have a good CS minor program even if they have a good CS major program). I have a lot of engineer friends (from my professional career or my time in school) who have little programming skill, but find themselves increasingly needing to program. Even the first 5 CS courses in most programs (versus the first 1-2, at best) would make them 10-100x more effective in their jobs.

A former colleague (EE) wrote test analysis software (we were both doing verification and validation work) that took minutes to analyze the data. My slightly improved version resulted in getting execution time down to seconds in the worst case (500MB file being processed). The improvement didn't need more understanding of programming than a 2nd year CS major would have, but he didn't have it because he'd taken literally one programming course (and never programmed again, except for small matlab things). I've seen similar things from aerospace and other engineers. Their code is usually correct, but often inefficient. Or they lack an understanding of the underlying memory model of a language like C and try to do impossible things (that, again, a 2nd year or so CS major ought to know).

So: Stay the course with CS if it is of real interest to you. Otherwise, look to double major or minor and use your CS skills to stay ahead of others in your discipline.

Thanks, that's a good point! I definitely am interested in the subject itself, and I think I would want to do it even if the money won't be as good as it is now, but it's hard to deny that's a factor as well. Mostly, I'm worried that there will be enough oversupply that there will barely be any jobs available at all, but it's reassuring to hear that may not necessarily be true.

I almost wonder if it would make more sense to major in CS and minor in something else, which would hopefully make it easier to specialize in a particular field rather than competing against a lot of generalists. I'm not entirely sure what else I'd want to do though, which goes back to the lack-of-interest problem that you mentioned. It's definitely something to think about!