I doubt Langi will ever contribute to the team more than on special teams and maybe as a rotational DT as an upperclassman. Most kids that are freshmen on a college football team have been playing the game for 10 years or more by the time they set foot on campus. Some rugby skills transfer over to football, but a lot of them don't. Plus, I don't care how athletic you are, it's almost impossible to play any position well at 410 pounds. He'll probably need to drop down to around 350 or maybe even less to be able to move the way a good DT does.
Langi's learning curve is going to be really steep, so I won't be setting expectations for him too high. Hopefully he'll surprise and turn into a great player, but the odds aren't exactly in his favor.