Reversing Language Shift

Is there anything we can do against that modern plague that contributes to endangering the languages of our world, called "language shift" (see our post below on language shift)?
One possible path to a better future for language diversity is "reverse language shift", abbreviated as RLS.
Joshua A. Fishman wrote a 415-page book that became a reference in the field, it is available on Google Books

Language Shift

Wikipedia has a brief article on a key concept for language preservation and revitalization.

Language shift, sometimes referred to as language transfer or language replacement or assimilation, is the progressive process whereby a speech community of a language shifts to speaking another language. The rate of assimilation is the percentage of... (More)