FWIW, a lot of open source caused other people to lose their jobs too, all pre AI. So what goes around comes around. The Free Software movement was from day one built on cloning proprietary programs - UNIX was a commercial OS that AT&T sold, the early Linux desktop environments all looked exactly like a mashup of Windows 95 and commercial DEs, etc. Every commercial UNIX got wiped out except Apple, do you think that didn't lead to layoffs? Because it very much did. Nor did it ever really change. SystemD started out as "heavily inspired" by Launch Services. Wayland is basically the same ideas as SkyLight in macOS, etc.
And who was it who benefited from this stuff? A lot of the benefit went to "megacorps" who took the savings and banked the higher profits.
So I don't think open source, which for many years was unashamedly about just cloning designs that were funding other people's salaries, can really cry too much about LLMs. And I say that as someone who has written a lot of open source software, including working on Wine.
Fwiw, AIX and to a far lesser extent Solaris still exist. I'm not exactly sure why people are using them (AIX I can maybe understand because "no one got fired for buying IBM" or whatever but there really isn't any excuse to be running Solaris nowadays since ZFS runs on Linux and and 2 of the BSD based systems and oracle seems desperate to let it die)