That is unlikely to happen. Crystal has no corporate backing, it has no distinguishing features (in comparison to other, more popular languages), and most of all, it has no Rails.
Crystal has Lucky and Amber — both are reasonable for small fun projects. They're still missing what makes Rails Rails, though. Rails is much more than MVC. It's the Ruby ecosystem and the tooling that really allow Rails to become what it is, and that is hyper-productive. You don't spend time reinventing the wheel, you spend time working on domain-specific problems.
Sure, chicken vs egg, but while everyone is hopping from language to language, framework to framework, packaging system to packaging system because they saw it on Reddit or HN, I'll be over here shipping Ruby and contributing to the Crystal ecosystem in my spare time.
Do you mean rails as in the framework people with choose crystal for? (It doesn't) Or a rails-like web framework in general? (it has https://amberframework.org/ )
Sure, chicken vs egg, but while everyone is hopping from language to language, framework to framework, packaging system to packaging system because they saw it on Reddit or HN, I'll be over here shipping Ruby and contributing to the Crystal ecosystem in my spare time.