Non-nullability is actually being actively worked on[1]. Currently language team is working on specifying the feature and figuring out the path towards it. [1]

Non-nullability is actually being actively worked on[1]. Currently language team is working on specifying the feature and figuring out the path towards it. [1] https://github.com/dart-lang/language/issues/110 https://github.com/dart-lang/language/issues/110