It is unclear at this point. If the sales of the core rulebook goes really well, and they get the greenlight from the Henson Production, then we may see future supplement published.
Last I heard, they were waiting (but not holding their breath) to see if Henson was going to reup the licence, since the original contract was for just the basic book.
That book, was actually trimmed down so that Henson would have less to work to do and the book would get out quicker. I think the extra material is the source of the bi weekly updates now at http://www.alderac.com/farscape/
