The last remaining person on Earth (let that sink in) to speak the Native American Wukchumni language was determined not to let it die with her. She stopped speaking the language when she was a young child at the death of her grandmother. She re-learned the language when her sister began teaching her children, and when she realized she was the last speaker standing, she dedicated seven years of her life to creating a dictionary of the language. During that time, Marie began to teach her daughter and her grandson, the latter of which, as you can see in the video, seems to have picked it up quite quickly. Since the dictionary, the three have spent time doing an audio-catalogue of the dictionary words so that the pronunciation would not be lost and most recently, they began teaching language classes to other members of their community.
One is enough. Believe.