With proper caching it could make local build systems obsolete for many purposes. Maybe it would be easier then to delegate module building in style similar to distcc, but less fragile.
I'm not intending to put you, your enthusiasm, or the people behind Modules down: I've been hearing that story since C++11 was still called C++0x (this might be an exaggeration) but I don't see anything happening in terms of standardization. And as long as modules are not standardized they are not going to see widespread adoption in C++ and certainly not in the open source community.
Because I like to walk down the memory lane I've looked at my HN comments regarding modules. Here is one from exactly one year ago [1], 855 days ago [2], 1100 days ago.
With proper caching it could make local build systems obsolete for many purposes. Maybe it would be easier then to delegate module building in style similar to distcc, but less fragile.