Where is Todd in the end? It is obvious he is picking up Leigh's mail, so did he move to her place in NYC? Maybe I missed a scene or bit of dialogue. I thought he said he would never leave due to his parents.
There is no spoon. - Neo
When she was saying goodbye to Jay, Leigh said that Todd was moving to NYC with her, at least until she found a new job.
I'd imagine that Matt's suicide woke a lot of things up in a lot of different people. I think it made Todd realize that he shouldn't hold himself back because, like Matt said, there's a whole world out there. Since he committed suicide, Matt never got that opportunity to explore, so I think Todd realized he was taking life for granted by wallowing around his old hometown because it was familiar and safe; I think he realized he had to start living in spite of the big, bad, scary world.
That was my interpretation anyway.