Ah the evolution of warfare. Less about making elite forces, more about deadly foot soldiers. It's funny that the thing that keep us from reaching doomsday weapon is the fact that there is no profit from total destruction.
Oh trust me, we HAVE technically already reached a "Doomsday Weapon"..
Just google
Project Sundial. Wild shit. Only never actually went through since its only use is literally just to
end everything.
Invented by Edward Teller (same guy who invented the hydrogen bomb, the upgraded nuclear bomb).
Also, Elite Forces are still very much important in modern warfare. Especially some of the U.S. Military's "Tier 1" units (DEVGRU, Delta Force, 24th STS, etc.) which are the best in the world. Deployed when it comes to highly-classified delicate, small-scale missions that need "no-fail" soldiers.