The implementation really is not built on top of GCL, the bulk of the standard library is persistent datastructure implementation and functional apis. The few cases here and there like `goog.string` can be removed over time. But really what's the rush? Large portions of GCL have worked unchanged for nearly two decades. Does Google archiving GCL make perfectly good code stop working?

When we eventually remove the direct GCL dependency it will sadly be more for optics than anything else.