I think I can mostly agree with the plan, but:
Improve language stability
Define appropriately fuzzily-defined areas of the language
(e.g. shared semantics, @property).
This is either a contradiction in itself, or "stability" actually
Foster library additions over language changes, and raise the
bar on language changes.
This needs to be handled on a case-by-case basis. The bare fact
that something can be implemented in Phobos or user code doesn't
mean it's a good idea. Both user experience and
correctness/safety need to play a higher role in the decision
than whether it requires language changes.
In particular, the stability argument must not be used as an
excuse to keep bad design decisions around for the indefinite