The logistics argument that helped the 308 continue to reign king is gone, which is why we see people moving from it.
In the past you had the argument for a 308 saying you can find it everywhere, it's the same argument the preppers make for .22s. Today that is out the window and yes, Hornady is responsible for making it widely available, which is a good thing.
The 260 suffered because of Remington, it did not have the foresight to promote it, but then again, very little was promoted then like it is today. If we go back to this site, and @Greg Langelius * called it here in 2001 that the 6.5 was the correct answer.
The issue with the 260 is, the caliber used to get loaded really long when using match bullets and they would catch the lands and pull out in a lot of rifles. It was hit or miss due to ignorance on what would work, how to adjust. We fast forward many years and the 6.5CM helped answer that question by being a tick shorter. It's the same argument the 6.5x47 made, we can load long and not catch the lands. It fit in a magazine.
to me, it no longer matters what 6.5, the caliber is beyond proven. The 308 is absolutely capable, we just decided to leave it alone rather than adjust it, which makes sense. If you think about it, you can do the same thing to a 308, figure out how to how to hot rod it a bit more drop the barrel life for a more efficient wildcat variant. Maybe it means creating a factory Ackley variant and dropping the bullet weight a bit. but why bother.
Here is your minute of Zen, this is an Army rifle from 2015, it's a 260 being field by the tip of the spear,
The recoil argument is super valid too,
6.5CM still makes sense in gasser with limited OAL mags.
I kinda fought it with my 260 and AICS mags and as a total newb listening to everyone say you gotta get cozy to the lands to get it to shoot well.
The long OAL AI type mags certainly helped to get up on the lands or now I run a long throat and use it to get extra case capacity and embrace the jump.
I personally like the 6.5CM as it totally improved the 260 situation.
I got my 260 just before 6.5CM dropped and the component and factory ammo selection is far better now than then.