I've never spent much time with Sun equipment, but the hardware and OS had features I haven't seen on commodity hardware with Linux. IIRC, Solaris could deal with an unrecoverable ECC error by killing the process that had the bad memory. And I think they had hot swap memory on some systems.

ZFS was pretty unrivaled for long term storage for a long time. Solaris zones were containers before they were cool. Dtrace is pretty neat. Etc.

Maybe they could have survived with their OpenSolaris push driving low end adoption and high end customers buying their hardware. Pretty sure they would have had to migrate to x86, but they were dabling in that.

Maybe make some low end commodity x86 servers. Sell enterprise a fully engineered big ass database server and a bunch of commodity web servers. Doesn't have to be exceptionally priced, just good enough to let customers have single vendor server purchasing instead of getting the big stuff from sun and the little stuff from dell or hp.

More systems consulting? Sun had great engineers, but you don't see too many war stories about them fixing stuff for customers (maybe they keep quiet though).