Without popular literacy, all but a few languages will soon disappear. It's not for lack of writing systems. Virtually every indigenous language has an alphabet or some other writing system. Most of these have been created by missionaries and linguists over the past 500 years. Nor is it for lack of bilingual education programs that teach children to read and write in their first language and the major language of their country.
Children typically learn to read primers and occasionally the Bible in their native language.
However, they rarely grow up to write books. In most cases, these programs don't produce popular literacy in the native language, and the tribal languages of the world remain largely unwritten. Moreover, many books go unpublished because the costs of printing are high. Nevertheless, there is no more potent force for literacy than authors who want others to read their work. Computers can help preserve language diversity by enabling native authors to produce literature in their own languages.