Star Wars: The Last Jedi - What The Ending Really Means

3. ...And Other Force Sensitive Characters

The very end of the movie reveals that there ARE other Force-sensitive characters dotted around the universe, and thus that there are potential students for Rey to teach the ways of the Force. That much is clear from the image of the stable boy showing off telekinetic powers (which he should definitely have put to better use actually sweeping the floor).

And on top of that little boy, there are definitely other Force-sensitive figures out there somewhere. During Luke's account of what happened the night he unwittingly created Kylo Ren, he mentions that Ben fled with several other students (no doubt seduced by his account of Luke turning on him).

Presumably, they became the Knights Of Ren, but it's not confirmed concretely. In either case, the story means that there are other former students of Luke Skywalker out there and they should be more than just a loose end when Episode IX comes around.