Kul Tiras was ruled by Admiral Proudmoore, but he evacuated it after Lordaeron's fall and began searching for any surviving members of the alliance. When he sailed to Kalimdor, he took control of Theramore from Jaina(who was his daughter) and started a war with the Orcs. The orcs drove him and his forces back to Theramore and Proudmoore was slain in the battle. Because Jaina didn't aid her father, Thrall let her and her people return to Theramore. So yeah, Kul Tiras has fallen.