Rogers and Hammerstein works aren't hundreds of years  old, representing ancient traditions now obsolete. My point isn't that we need to live and die by our traditions, simply that this role isn't predicated on the Asianness of the performer; most companies have seemed to simply put in some "ethnic" performer. To my mind its almost worse, to act like just any Asian or black or latina will do to replace an ethnicity and its unique experiences in that time, place and social context. Some notable productions have gender swapped with a firm intention to subvert expectation, but to cast a Korean or a Japanese in a Philipino or Vietnamese role and declare it to be an adequate representation of a specific ethnic experience is somewhat distasteful all on its own. If we must be so specific as to cast the right ethnicity, I welcome you to point out the large quantity of Tonkinese-Canadian opera singers that must surely exist in this country.