The tagline for the movie was: A Generation's Final Journey Begins. Which leads me to believe their intention was to make a trilogy, in the same way that TWoK, TSFS and TVH were trilogies with events following very closely the end of each movie. Nemesis seemed to leave a lot of things up in the air that could have been addressed in a followup. At the same time, it seemed like a passing of the torch to Riker and his crew, and I think a followup movie would have followed him (seeing as we never actually got to see the Titan on screen) and explore the idea of peace with the Romulans, closing the book on a chapter in the process. I don't think Picard and his crew would have been completely off the table at this point, as I think they could have gone back and forth between both crews and perhaps reuniting at the end. When Nemesis ended up not being successful, it changed everything, and I feel it's a shame we never really got to explore the aftermath as there were some interesting possibilities that had opened up. Ending the movie with the Enterprise at DS9 and replenishing its crew, with Riker boarding his new ship and going off into the sunset err wormhole would have been pretty sweet.