All our production stuff was being deployed on Aix, HP-UX, Solaris and Windows NT/2000 Server.
Likewise most of my university degree used DG/UX and Solaris, when Red-Hat Linux was first deployed on the labs, it was after the DG/UX server died, and I was already on the fourth year of a five year degree.
We did use NT/2K internally but that was because we had some who insisted on using SMB via Windows.
Such fun times. The nix and nix-like OSes were spreading like fire. I never would have thought I'd ever wrangle them for the majority of my career.
Just because things hung around didn't mean that Sun/Solaris/Java were long for this world. Linux/x86 was just too cheap compared to SPARC gear. Even if it wasn't as robust as the Sun gear, it just made too much sense especially if you didn't have any legacy baggage.