Got the link from Chris Chavez of Sports Illustrated.
Basically, when asked about the mile he said he has run 2:07 for 800 and "of course" he could break 5 for the mile.
2:07 answers some questions as I'm sure people have debated his 800 as well, but I'm not convinced he could break 5. I knew kids in high school who could run 2:07 but only ran 5:00, and they did distance training. I sure Bolt hasn't run a mile at anything faster than a jog since he was a boy, but from 45/400m to 2:07/800m is a big drop off.