* Subract: Removing parts of the language - let crockford free to rip out the bad parts.
* Enhance: Bring in some more taste of Scheme.
* Replace: New scoping for var etc, without introducing new keywords.
I'd prefer to change the semantics than introduce new keywords. Of course there are two schools of thought - I favour a small language over backwards compatibility. (And interim tools for migration).
Where I do favour extensions is for expressiveness or performance reasons.