Accessibility of FPGAs has made massive strides since 2000. You can nowadays get people build a really basic FPGA demo in an hour, starting with a dev board and their unprepared laptop, and even I remember times where you'd struggle to get the tooling installed in that time.

(Not going to go into "mainstream", because that's a) incredibly vague (is microcontroller programming "mainstream"?) and b) IMHO not that interesting - it's fine for specialist things to be accessible but not mainstream)