Ask HN: What happens to older developers?

I started wondering about this in the recent STEM thread. As someone now in their early 30s I'm starting to wonder what the mid-late career as a software developer looks like.

Do you have to go into management to continue progressing upwards in pay and influence? I know this isn't the case at some companies (e.g. Google), but is it rare or common to progress as an individual contributor?

Is there a plateau in pay? Is there a drop in pay switching jobs after a certain number of years experience because places are looking for 5+ instead of 20+?

Are older devs not looking for new jobs because they have families and want more stability/are focussed elsewhere?

Is becoming a specialist rather than a generalist the answer?

And lastly: if you're in your late 30s, 40s, 50s, what are you doing at your job? What are the older people in your workplace doing?