In the 90s it was difficult to imagine Novell ever fading away in the enterprise server market. There was no alternative comparable to Netware and NDS. Microsoft completely killed them off with NT Server and then Active Directory with Win2k. We had around 50 clients running Netware, and within 12 months of Active Directory being released, we had switched almsot all of them over to Windows (usually with Linux servers…
So if you wanted to run any 3rd party software on your Netware servers you were making a big bet on both its stability and safety (in not scribbling over the rest of Netware, including most especially whatever memory it was using to keep track of files and directories, no matter whether it had all of the latter in memory or not).
As soon as NT became stable enough (which didn't take very long at all as these things go, that group really had its act together from launch to 3.51 SP1) the value proposition was pretty clear and simple: run Netware for file and print services or run NT for both plus whatever other server software you might want (NDS was never a big issue for the sorts of systems I was involved with so I don't know the story there).
So as I recall the bleeding started before Win2K, although I can see becoming critical with the release of Active Directory.
Of course, all this assumed that Novell wouldn't make the proper strategic decisions in time, but it didn't take too long to realize they just didn't have what it took in that area.