[wahern]

Technically SPARC is an open standard, and importantly Fujitsu sells their own hardware. OpenBSD has done some pretty cool mitigations on SPARC. What killed SPARC was that there hasn't been entry-level hardware for over 15 years. ARM become popular because of things like the Beagleboard and later Raspberry Pi. Enthusiasts and developers could experiment and familiarize themselves with the ecosystem, building mindshare and expertise.

Sun would have done better to have made SPARC hardware more accessible than to have open sourced Solaris. Hindsight is 20/20, but now that we've reached the limits of single-threaded performance Sun's emphasis on multi-threading and specialized ISA extensions would have made both Solaris and SPARC competitive today.

Getting there would have required cannibalizing their enterprise income, though, and that's difficult if not impossible for any company to do. They made the gamble on Solaris because it was less risky--major enterprises were always going to stick to Sun's Solaris--but low-end SPARC hardware absolutely would have hurt their bottom line.