I too wished that Farscape had a Season 5 but I also believe that Peacekeeper Wars was a perfect finale to the show. After watching it, I felt completely satisfied. No, we didn't get to see the return of the Nebari or their plans to take over the galaxy. No, we didn't get to see Rygel's return to his homeworld and him reclaiming his throne. But we basically know that Rygel is on his way to doing that after the miniseries and honestly, after watching the finale, the Nebari threat didn't really seem that important. They could easily be put in the box of future adventures John and Aeryn will go on in the show's off-screen future that are better left up to the imagination.