Linux killed the Workstation vendors stone dead. Sun seemed to be very aware of the problem and fought really hard, but they couldn't cut off Linux completely.

I went to a seminar by an Open Source hacker at a Unix user group conference in the late 90s, where he talked about the Sun funded work he'd done on getting the Linux kernel to run well on Sun workstations. He was absolutely clear that he thought Linux would kill Sun because it completely undermined their software license business, but that this was their problem. They just had no good options.

I suspect the reason IBM was able to reconcile with Linux and even go all-in on it was that it complemented their lucrative very high end server and mainframe businesses. Their workstation businesses benefited from a halo effect from the super high-end mega-systems that protected it from becoming total road kill, but Sun and the other vendors never really managed to establish themselves at the super high-end, so when Intel ditched Itanium and PCs caught up with RISC they were left without a market.