It was Roberta and Ken Williams...What ever happened to them?
They sold Sierra to Vivendi in 1996. Roberta's last game with Sierra was the eighth King's Quest
game Mask of Eternity
, following which she promptly decided to take some time off. Mask of Eternity
proved to be a disappointing game, critcially and sales wise, due to a largely misdirected attempt to bring the Adventure Game genre into 3-D (the game had more melee than puzzle solving).
Ken left shortly after Sierra was sold to form WorldStream Communications.
Roberta still keeps up with the adventure game scene and reportedly still flirts with the idea of coming out of retirement, but has yet to do so (the latest interview I could find with her is dated 1999).