sorry it took me so long to get to your question that you seem to have felt a need to resend it. bluntly, it's the wrong question. the GNU system is a concept, not a collection of software components. the GNU project even selected some non-GNU components to be part of the GNU system, because they were already freedom-respecting, so there was no reason to replace them. the defining feature of GNU is that it's an operating system made with the explicit purpose of enabling users to do their computing in freedom. it set out to do so starting from a unix system and replacing proprietary components one by one. when it was nearly there, already in wide and preferred use on top of various unix systems, someone else implemented the last major missing piece, and a while later released it as freedom-respecting software. though this last component wasn't made sharing the purpose of gnu, nor to be part of the gnu project, it was designed and implemented to work with gnu and so, once it became freedom-respecting, it was thus a good fit in a gnu system. (to be continued)