The Crystal Programming Language Forum

Is this a road to some crystal-to-all-platforms rails?

Following the path taken by http://www.lambdanative.org/ might allow to put some rails down, for cross platform developments that include native mobile apps.

Maybe later even the web (amber / lucky / WebAssembly)?

Lambdanative is an example of a lisp interpreter + compiler based project that has already matured to some degree over the years. It currently provides scaffolding and a non-native-ui, same-on-all-devices approach to widget drawing based on the glgui OpenGL library.