I have heard from a trusted source few months back that there are talks in WMF to rebrand all sister projects under the name Wikipedia. If that happens some day, Wikisource will be no more as it is and it will be called something like Wikipedia-source etc. The logic for this kind of step is that people doesn't know or understand Wikimedia, but everyone knows only about Wikipedia.
I think, the recent blog in the Foundation site is the first step to do such things.
IMHO, very few people know about sister projects, because they didn't get the love they needed from WMF or other affiliates. Everything is so Wikipedia centric. But that can't be the fault of the sister projects.
I hope this rebranding doesnt become true someday.