There is no fan creation that could ever be FS3.. even if HLP held the IP (which is very, very unlikely).
There might even be some objection to calling Blue Planet FS3 correct?
BP is a cool thing, but it is actually never FS3. While
probably played with the idea to add new species (the Ancients), I massively doubt they'd ever done something like the Vishnans (in fact, their concept is contrary to Canon, which had the Shivans being both Destroyers and Preservers).
It's like Sync/Transcend, but much more complex of course - something that if you unbind the story from FS you could easily sell as a book, but not necessarily a FS game.
Even INF, which is pretty much what everybody believed to be what FS3 would be like for a long time - first fighting Earth, than the Shivans - is apparently something different to what Volition intended if you read the interview thread carefully.