As a National Board Certified language teacher I just speed to say one thing...being a "native" speaker of the language does not a good teacher make. I teach Spanish, which is my second language, and have been recognized as a good teacher. In fact, having learned the language at least partly in a classroom, along with my methods training, language acquisition study, and travel to several countries and regions whe the language is used, I may be even more able to teach about the language and the related cultures than someone who simply grew up speaking it. There is more that goes into planning good instruction than you might guess.
I am not suggesting that native speakers are all UNqualified. Just that being a native speaker with amazing language skills doesn't make you immediately a stellar instructor. Whoever teaches a language SHOULD have great language skills also...but if they know the language and know the culture, and can somehow connect students to that culture, and maybe the local community, and know how to teach effectively, isn't that what matters?