Wariner was at one time the second fastest man of all time (is he 3rd or 4th right now?). We know that we lose speed as we get older, but as Haile, Paula, Bernard, Meb (not sprinter, I know) have all told us: endurance can improve with age, it's only a question of staying injury free and not killing workouts. Even if his speed has come down a lot, I bet he still has better 400 potential than all but a handful of World-Class 800 guys, a healthy Rudisha being an obvious example. Who doesn't think that a healthy Wariner couldn't beat even the likes of Duane Soloman in a 400?
Did you watch his 800? First of all, the time didn't mean anything. I think it was an obvious learning experience. He ran the race tactically perfectly, considering his strengths. He won with ease on the stretch, and after watching the race, it seems to me that his goal was to find out what the last 100m of an 800 feels like. I believe he ran in the slow heat just to see what those knuckleheads would throw at him.
I am using hyperbole, of course, when I say that he could be an olympic finalist, but I honestly think he has all the tools to race an 800 at the top level, and I am predicting that he will attempt a more serious effort in the near future. If he can make the right steps, I wouldn't at all be shocked to see him in Rio next year.