If you're counting all desktop/server computers, Linux has way more market share than all of the Unices ever did. It's probably even true for desktop Linux. If you count mobile phones, Android is a Linux derivative, and iOS is a BSD derivative. The fundamental issue for the workstation vendors was simply that with the P6, Intel was near parity or even ahead of the workstation vendors in performance, and it cost something like 1/4 as much.