Here's the true test.
As I noted above, Jesse Owens's 1935 LJ would still have been good enough to place him on the U.S. Olympic team in 2000 -- 65 years later.
According to Carl Lewis's athlete bio at http://www.usatf.org
, his LJ PR is:
(presumably from his '91 WC battle with Mike Powell).
So, will a jump of 29-1.25 still be good enough to make the Olympic team in 2056 (1991 + 65) ?
The only way I'm going to know for sure is if I live to 94.
We'll know sooner (perhaps within 10 or 20 years) if one or more U.S. jumpers start hitting 29-6 (which would be a pretty strong sign).