As gray dog around the prairie, had Microsoft actually been serious with POSIX subsystem on Windows NT/2000, instead of some marketing material and low level effort, GNU/Linux adoption would never taken off, at least not at a level that would have mattered.
With OS X on one side, and POSIX subsystem on Windows NT/2000 side, everyone would be doing their UNIX like workflows without thinking once to try out GNU/Linux.
At my university we only cared about Linux on its early days, Slackware 2.0 days, because naturally we couldn't have DG/UX at home, and that POSIX support was really unusable beyond toy examples.
With OS X on one side, and POSIX subsystem on Windows NT/2000 side, everyone would be doing their UNIX like workflows without thinking once to try out GNU/Linux.
At my university we only cared about Linux on its early days, Slackware 2.0 days, because naturally we couldn't have DG/UX at home, and that POSIX support was really unusable beyond toy examples.