But we kind of do, BSDs are enjoying lots of upstream changes from Apple and Sony.
And in what concerns x86, they would just support it as well, as Solaris did. HP-UX and Aix also have supported a couple of CPU architectures, as did some of the others.
Just Irix was kind of married with MIPS.
Or Windows would just have won the x86 server room instead.
In any case, there are a couple of major surviving GPL projects, all competition against Linux on the IoT space are BSD/MIT FOSS POSIX clones, ironically one of them being sponsored by Linux foundation (Zephyr), so those around in 20 years will get to appreciate how much of GPL will still be left around.