I would like to point out that as far as the movies go: what we have learned so far from the movies holds true as far as Luke and Leia and their offspring being the only Force Users in the current timeline.
There's absolutely nothing in the movies that says Luke and Leia are the only Force users in the entire galaxy. The only thing remotely like that is Yoda saying they are the last hope. That's more likely pointing to Luke and Leia being Anakin's children and being powerful Force users. That's a HUGE jump in logic to believe that means they are the only Force users in the entire galaxy.