Do you think a similar series of events are unlikely to play out when you look at the microprocessor field right now? I see similarities in that there essentially are no open source processor options (MIPS is the only one I can think of off the top of my head). Intel, AMD, IBM, TI, ARM, Qualcomm, Oracle, the lot of them are closed source and I would think the same benefits that came with an open source operating system would come with an open source processor architecture.

That said, I think the biggest difference is the parity between OSes in in the 70s vs ARM/Intel's current dominance. That's definitely going to make it more difficult to get people to adopt RISC-V. I'd imagine if there was any likelihood that IBM, RedHat, Google, or Intel could customize a RISC-V chipset to outperform (whether it's TWP, flops/sec, whathaveyou) any current offerings they'd pour dumptrucks of money into it just the same.