Various things, a common aspiration was to try and fast track to a management position at a consultancy or blue chip where things were are more about spreadsheets than code. Others do technical work, but not strictly development like Q&A or technical support.
Some went into academia and some did other things altogether, I know at least one person who became a tree surgeon and another who is a session musician.
There are more jobs available, especially in places without software companies. Or people take those jobs temporarily while they look for other jobs, get promoted and end up following a different career track.
I'm fond of developer-QA folks that automate most of their pointing and clicking. There is, absolutely, a skill in finding bugs by exploratory testing, but someone who can combine that with automating previous tests (thus building up a regression suite) in a way that's maintainable is a real keeper.
Some went into academia and some did other things altogether, I know at least one person who became a tree surgeon and another who is a session musician.