Elmer Keith was not a recoil junky by any means.
He did not invent the .357 Magnum or the .44 Magnum.
He was known to "hot-rod" cartridges like the .38 and .44 Special, but only because he started with what were cartridges at black powder pressure levels.
He disliked the .454 Casull and dismissed it as excessive and unpleasant.
He did invent a .41 caliber rimmed revolver cartridge that Remington loaded in excess of his wishes and named the .41 Remington Magnum. Had it instead been to Keith's specifications, it would have been similar to the .40 S&W but 26 years ahead of its time.
Speculation about far-future technology is moderately amusing, but a discussion of the next innovation, rather than dozens of innovations into the future, will have to consider that for the time being, "The laws of physics cannot be denied: minimal recoil is inconsistent with maximal tissue disruption" (a quote from Martin Fackler).