I think it's fair to say that Haile's marathon WR will eventually be lowered- if not by Geb himself then by Bekele or Ryan Hall or one of the other likely candidates. And while the future record may dip into the 2:03's, I do not think we will ever see sub 2:03. This opinion is based on the rate of progression of the record since Clayton, as well as the opinion of Ron Hill himself from Noakes' TLOR- that 2:03 is at the very outside limit of human possibility.