Somebody tell me what happened at the very end (had to leave a couple minutes early)

Older Will was challenging his younger self to a race around the campus track to prove that he still had it. Then the movie faded to black.. So you didn't miss anything.

Younger Will is walking with his classmates, sees older Will and the girl, waves to them and comes over. Older Will gives him fresh documents - a passport, a birth certificate, driver's license, and mentions that he liked the name younger Will has chosen for himself - Jackson, like their biological mother (her family name, presumably).
The girl asks him if he has chosen a major yet, and he replies that he is thinking about engineering. Older Will says that he should pick Computer Science. The girl tells him that he should start with humanities and then choose engineering as a graduate degree. Then there is some banter about both Wills' looks and physical shape.