Looper has been a great success so far, so of course there is a lot of speculation about if, and when, there will be a sequel. The director, Rian Johnson, has said nothing about this yet, but the movie has so many fans that they are already discussing the possibility.
It has to be said that the film doesn't really lend itself to a sequel. The plot is self-contained and the ending isn't open (no spoilers here, so I won't say more than that!) Of course a second movie could follow the example of the Terminator films and others, and go back to an earlier time - which would make it more of a prequel. Or it could go much further into the future.
So there is always scope for a sequel, and it will be tempting to build on Looper's success, but on the face of it this movie was not conceived with any further films in mind; and some fans are saying that it's a great one-off and should be left as it is.