I think it's a bit disagenuous to write Cam off as just a 10K runner. Obviously he is a very special athlete over a range of distances - 8:13 for two miles indoors, with apparently limited tapering, is a very good performance. Cutting his mileage back a bit, and including a bit more quality in his training would seem to be an obvious path towards running fast at distances as short as 1500 metres. Didn't Galen Rupp run 3:34 last year - how many Americans bettered that?