People keep asking what's the best thing to do to ensure more people work with Ruby in the future.
Answers like "build more things in Ruby", "contribute to Open Source projects" are vague, not clearly defined, and un-actionable.
Create an apprenticeship program for developers who are still in school. They usually want to learn how "real-world" development is being done and are eager to learn.
Make Ruby the first programming language for them and you'll have a passionate Ruby-ist for life.