The only people that had their number retired are Calvin Jones, an All-American lineman that died in a plane crash #62, and Nile Kinnick, Heisman Trophy winner that died in a plane crash #24. AC will not have his number retired. Not if someone like Chuck Long didn't
Like others said, sadly he would have to die. If Ricky Stanzi won the heisman and say threw the game winning touchdown in the NC game i could see #12 being retired.
The bar is set incredibly high and that is okay with me.
Just wanted to add that Cal Jones wasn't just an All American. He was the Outland Trophy winner and the first African American recipient of that award. He also chose Iowa over Ohio State. (gotta love that)