(This may go unanswered for a while due to not much Starfinder lore being released, but I feel like it's worth asking now.)
After the conclusion of Rise of New Thassilon (the most recent Adventure Path) (spoiler alert),
the only two runelords who survived were Belimarius and Sorshen, with a new faction emulating the runelords' magic and trying to become runelords as well. It's likely that at least one person from that faction succeeded before the Gap.
It's known that Starfinder is in Pathfinder's direct future, and all runelords are immortal.
In addition, Sorshen has the immortal ability from being 9th mythic tier, so it's incredibly unlikely that she in particular died from violent means.
Has any information been revealed that any runelords are still around as of Starfinder? Any evidence to the contrary?