I think that's a mistake in the article, we will follow semver after 1.0.0, and we definitely don't want a 2.0.0 less than two years after 1.0.0. I'm sure crystal will provide the same stability guarantees as go and rust.
My main concerns are development time and tooling. Crystal looks great and offers some great features that no other native-compiled languages really offer at this time (which is amazing) but I am the kind of person that needs first-class IDE support to take a look. I think crystal would be the perfect platform for some great software development.
Aside from tooling I need a guarantee that my code, if following all of the best practices, should be compilable from now till the foreseeable future.