If you have an OSFAMILY variable, all of these lines collapse into an unconditional:
````
include $(ROOT_DIR)/make/$(OSFAMILY).mk
````
with the expectation that each OSFAMILY will have some OS-specific variation.

I can see where you're going with the $(OSFAMILY).mk concept.  It does seem a bit premature to do this since there really isn't much in those files but as long as it's clear exactly what sorts of things should go in there, I don't mind splitting them out.

You mentioned that you have other follow-on changes in mind.  What sort of things do you foresee putting into these files?