I'm of the opinion that powerful enough reflection + metaclasses (e.g. with the ability to synthesize almost arbitrary code ) would be able to transform a lot of language features (noexcept, coroutines, ...) into library features. But it's not possible for all, and you'll pry auto, range-based for, atomics semantics, lambdas, restructuring bindings, and brace-init... from my cold dead hands