If you build one new feature that subsumes N>1 old features then you're effectively shrinking the language because you never need to use those N old features any more. You can then support legacy code with macros that compile the old features into the new feature. At that point you've actually shrunk the language. You can even have those legacy support macros give compile-time warnings that the old, now-deprecated feature is being used and that the code ought to be changed. In fact, you can even easily write tools that will do this translation automatically. So yes, you really can shrink the language.