In the last 10 seasons, only twice has an ethnic minority player NOT made final tribal (Philip, Albert, Sabrina, none for caramoan or phillipeans, gervase, woo, Natalie, will, Tasha/Jeremy
That's pretty good considering only a few are castes each season. Looking farther back at seasons it becomes more sparse as you go, save the seasons where Survivor really pushed the diversity (cook and Fiji)