The American, who reduced his own world mark of 19.66sec to 19.32sec at the Atlanta Games last month, said he did not know of anyone likely to better it - although that could change by the Sydney Games in 2000.
"Of course it's possible to improve it but I think it will be very difficult," he said in Milan before the Grand Prix athletics finals on Saturday. "I think it could only happen in a competition like the Olympics, where there is an extra incentive."
Liz McColgan, who had an unhappy Olympic marathon, will seek consolation at the World Half-marathon Championships in Palma, Majorca, on 29 September. The 32-year-old Scot leads Britain's team in an event she won in 1992, when it was staged for the first time.
McColgan went into the Atlanta race with a swollen heel, and finished 16th. Her first race back will be the BUPA Great North Run, also a half- marathon, on Tyneside on 15 September.
BRITISH TEAM (World Half-marathon Championships, Palma, 29 September): Men: M Jones (Horwich), P Makepeace (Leicester), C Robinson (Spango Valley), D Swanston (Copeland), D Tune (Rotherham). Women: H Heasman (Horwich), L McColgan (Dundee), D Sanderson (Watford), H Nash (Newport), S Goldsmith (Edinburgh WM).Reuse content