I'm writing this out of respect to the best 800m runners, and because of the crap that I keep seeing written about Wariner's potential at 800m. Just becasue Wariner runs a fast, smooth 400m AND is skinny, this does not mean that he could be the most incredible 800m runner ever.
No doubt, he's an incredibly talented athlete - but it requires a whole diferent athlete to succeed at 800m than it does at 400m. Wariner ran about 20.5 for 200m IN HIGH SCHOOL! now that should tell you that he's a speed based athlete (who also has exceptional speed endurance). 44.3, while very impressive, is not out of this world for someone with his speed. He certainly would appear to be good enough to train his way (over a few years) to maybe a 1.45, but no faster I don't think.
And please, don't let me hear any other people saying 'oh, but think how easily he could run the first lap in 49 and then all he has to do is another 51 second lap and he's run 1.40' ... or something along those lines. I'll leave you with Peter Coe's quote some years ago when Edwin Moses suggested how easy that might be.
'yes, he would go through the bell in 49 and it would be very easy for him. He'd run well down the back straight, but then at 600m something very strange would happen to him, something he would've never experienced before. And that last 200m would the slowest and most difficult 200m he'd ever run'