Consider what "standard" really means. That name was originally applied to songs that were so popular and well known that many live performers included it in their repertoire. In the days before LP's, most performers made the bulk of their living playing live in clubs, concert halls, or on the radio. And, few performers wrote their own songs in those days. The songs by Gershwin, Irving Berlin, and other composers of popular songs became "standards" because every performer was expected to know them. All of that has changed, but there are still some newer songs that live performers who frequently sing material that others have written are expected to know. McCartney's "Yesterday" is now a standard.
I recall that back in the 1960's, when lounge-act singers were making their last stand, and performers like John Davidson, Robert Goulet, Sergio Franchi, Bobby Darin, Wayne Newton, and all of the other handsome, tuxedo-clad "Vegas" acts were attempting to follow the footsteps of Sinatra, Martin, Bennett, and the greats of the 1950's, you'd hear lots of pop and rock songs covered with Nelson Riddle style accompaniment on the TV variety shows that were common in the 60's. Often, the results were more comical than anything else, but sometimes a rock song would actually sound good as part of a lounge act. Much of Neil Diamond's stuff worked well in that context. I can imagine "Every Breath You Take" working in Branson, Missouri as part of Bobby Vinton's act.
With the comeback of lounge music as a resurgent genre that's finding a new audience who either is into "retro" or else who genuinely likes that kind of music regardless of when it was popular in the past, we should be hearing even more rock and pop classics turning into "standards". The thing about those songs getting on the radio is that the suits programming stations might be convinced that "Every Breath You Take" is now a standard as a song, but fail to realize that to fit on a standards station format, it should be a cover of the original performed by a "standards" singer, like Michael Buble or Harry Connick, Jr.