I really can’t say, I’m not privy to any of the outer solar system projects that might be in the works. Voyager was originally intended to do flyby of the outer planets, and then it headed out of the solar system. I think the trajectory was always designed with the idea that it could exit the solar system. As far as I’m aware, we’ve done a few missions to asteroids, but nothing that is going out to do flyby of the outer planets. But, I could be wrong, don’t take my word for it. All of the stuff I have worked on has been near earth, or pointing away from the earth but still within the vicinity of L1 and L2 Lagrange points.
You’d be surprised how many missions nasa has in the works at any one time.