This Brit doesn't seem to think so
http://www.sportingnews.com/sport/story/2015-03-27/could-usain-bolt-break-the-400-meter-world-record
I don't agree with what he said. Bolt is an exceptional athlete and he's tailor made for the 400. He would have to train hard to get it, but he could do it with room to spare
He nearly broke Johnson's 300M record without even really trying. He didn't even train for that.
Not saying it would be easy, but of course he could. I would say two years training tops would be all he needs. After the '17 WC and he gives up short sprints
As for will he do it, that's a bigger question. He claims he will retire after '17, but he's made all kinds of remarks he later didn't follow through on. He is lazy, but if he gets bored it could challenge him.