Good guy Nintendo isn't working on any paid DLC for Super Smash Bros. because they don't want people to feel shorted. In an interview with Videogamer, Sakurai said, "I understand that DLC could add a lot to the appeal of Smash Bros., and I appreciate that a major part of the excitement for these games come from which characters will appear in the roster, so I think fans could really enjoy DLC that could keep this excitement going. However, I think there might be criticism that we are cutting up content to sell characters one by one, or that we are adding things later that should have been there from the start."
Creating a character is a lot of work and costs a lot of money, says Sakurai, and he doesn't know that adding more DLC characters would be worth it. Unfortunately, that also means he thinks adding characters like Reggie and Iwata isn't a good idea. When asked about it, he said, "I don't think the inclusion of these characters would be very interesting to a wide audience. For the amount of effort involved, I would actually prefer to add another roster character. As it takes a lot of work to add a character to the game, it's not a decision that can be taken lightly."
For now at least, it looks like Mewtwo is the only DLC character we can look forward to.