I hope we won't get builtin RC, but that's off-topic.
In any case, there has been talk about introducing finalizers instead of destructors for GC managed objects. rt_attachDisposeEvent() already exists and is used by std.signal for weak references, but it's a hack, it needs to be formalized.
These finalizers can then have much more restricted semantics than destructors, e.g. they must be callable on any thread, are generally un-@safe if they access members with indirections, and so on.
