This seems to be a debate alot of people have. I just spoke to El G and his coach seperately and asked them the same questions. Hicham said 49-50 seconds for 400m and 1:45 for 800m. I then asked his coach the same questions-he said he has run 48 for 400m and 1:44 high for 800m in training. He said he would do 4X800m at 1:48 each with 3min rest between them in training. He said he thought he could probably run 1:43 low at 800. I also asked about the 5000m-he said he believed that if Hicham continued to train with that as his goal if he woudln't have called it quits and run a few more years he believed he could run 12:30.
I am now kicking myself in the head for not asking him about Komen's 7:20 to see what he would say about his potential to go after that OR it being out of his reach even.