As it turns out, Tatum has a supporting role in the upcoming Ron Howard comedy THE DILEMMA and it seems he was good enough in that to convince the JUMP STREET team he’s got the chops. And besides, the character, as written, is called both a “f*cking idiot” and a “f*cking retard” by Page 5 of the script. (This is not to say that Tatum is either an idiot or a retard, just that I buy him as a dopey, hot-headed cop.)
Tatum and Hill would play two 23-year-olds who have difficulty working undercover because of their youthful appearance. That leads them to the high school beat and 21 Jump Street.
Emma Stone had been in talks to join the film but it looks like her work in SPIDER-MAN will preclude her from joining this film (unless Sony decides to postpone JUMP STREET but that’s unlikely).