I deeply believe that if Windows NT had a proper POSIX support, instead the half heart attempts Microsoft was doing, around 1996 no one would have bothered to install Linux.
I had access to Windows NT and ended up getting my first distribution via the Linux Unleashed book, because I needed something at home to save the trips to campus to work on our DG/UX timesharing environment.
If the POSIX subsystem was up to it, I wouldn't need to look elsewhere.
Another what-if scenario is what if Sun, or some of the other Unix vendors at the time [1], had aggressively sold 386 Unix OS'es for clone PC's at a modest price. Aiming for the mass market rather than the low volume high margin workstation business. The world could have looked very different then, Linux might never have seen the light of day, and maybe even killing off Microsoft's ambitions in the OS space beyond DOS and windows 3.x.
[1] Just picking on Sun because they had the Sun386I back in 1988 and the 386 port of SunOS to go with it.
The original NT POSIX subsystem feels like it was there to check a requirements box. Microsoft Interix (originally Softway OpenNT) was really nice, though. I remember playing around w/ it in 2000-2001 and being amazed and what would compile and run.
I had access to Windows NT and ended up getting my first distribution via the Linux Unleashed book, because I needed something at home to save the trips to campus to work on our DG/UX timesharing environment.
If the POSIX subsystem was up to it, I wouldn't need to look elsewhere.