I get the nostalgia, like classic cars, but a car you've spent a year's worth of weekends fixing up isn't a daily driver.
Yeah well each to their own. That description fits the 36 year old car that's my daily driver pretty well.
Some of the extensions I maintain, like rsyslog and mariadb, require that the CPU be set to i586 as they will no longer compile for i486. The end is already here.
Some programs like Firefox have required SSE2 for a long time already, but the range of programs one can really run on a 486 is limited anyway due to its performance. Firefox is now in the process of dropping 32-bit Linux support entirely, which unfortunately might be the next stage for some other software projects too.