I thought then and still say that had Novell ported IPX/SPX to Unix[0] (they did own Unix in the 90s), Microsoft would never have been able to make them irrelevant.

Because the biggest reason Netware lost was the inability to develop software on the platform.

This severely limited the value of Netware as a server operating system, as developers (for the most part) prefer to develop on the the platform (cross-compiling for other flavors of *nix doesn't count) for which they're developing software.

What's more, IIUC, the development tools for Netware were just awful. Which additionally limited the number of developers working on Netware-related applications.

And even those few folks mostly abandoned it as NT gained popularity as a server and a development platform. Had there been a robust user/development environment (like Unix), that likely wouldn't have happened.

[0] I am aware that Netware was mostly written in x86 assembler, but porting IPX/SPX and a few other bits and bobs would have allowed Novell to migrate to a Unix platform without having to rewrite the entire OS.