Briefly:
- Base: minimal stdlib replacement. Portable and lightweight and intended to be highly stable.
- Core_kernel: Extension of Base. More full featured, with more code and dependencies, and APIs that evolve more quickly. Portable, and works on Javascript.
- Core: Core_kernel extended with UNIX APIs.
None of these are going away. The most disruptive thing that we’ve discussed is adjusting the boundaries between Core_kernel and Core, e.g., Core may become the portable one, with unix dependencies moved out to a separate package. That said, such a shuffle is not coming soon.