I honestly doubt this will become the case. I think it will carve out a decent niche, and remain there. I don't see it dominating other already established cartridges because I don't think it has a lot to offer over other established cartridges in ways that most hunters and shooters need.
Most hunters don't need a 6.5 CM and most ranges don't extend to the lengths that would make a 6.5CM a better choice than a 5.56 or .308 for plinking or even moderate target work.
You've got that right, but also 90% of people will be suited just fine with much cheaper alternatives such as the aforementioned options, 5.56 specifically...even less recoil and cost to handload or purchase.
As a hunter, I can tell you that in my circle and people I'm exposed to... the 6.5CM is getting almost no play. As I said, it does nothing for the vast majority of hunters that other established cartridges haven't been doing for decades. I also think the modest reduction in recoil the 6.5 CM has over other cartridges is a point overplayed by fans of the 6.5. I have spoken with a lot of hunters and the consensus seems to be that the capabilities of the cartridge is vastly more important than the felt recoil, and that erring on the side of caution is the preferable option.
Around here, I predict the 6.5 CM will be a fairly popular option but will by no means approach or eclipse the popularity of 5.56 or .308 for plinking, and will not come close to beating out the popular calibers for hunting.
As for reloading, I am in the process of choosing an upper for an AR10 and have no interest in a 6.5 CM upper, will go with a .308 upper, because the 6.5 CM
1. Does not do anything better than the .308 for hunting at normal and ethical ranges
2. Does not have the power for me to consider it an ethical hunting cartridge at the ranges it does start to shine over the .308,
3. Components for the 6.5CM are much more expensive than the .308 for reloading. 7.62 LC brass and pulled 147gr. bullets are hard to beat for plinking, LC brass and premium expanding bullets are no more expensive for the .308 than the 6.5
4. 6.5CM does not punch paper any better at the 400yd range I shoot at than the much cheaper to load 5.56
I predict the 6.5 CM will establish a niche for long range plinking, and as a pretty good medium game cartridge. I would be very surprised if it came to be much more.
I actually think JMR might we'll be right, at least where I'm at, and at least for a little while.
I'm seeing fewer and fewer .308s and .243s in use these days, and more, and more 6.5s
Nearly everyone I know, who owns more than one rifle, owns a 6.5CM.
Loaded ammo cost isnt that much different. 20 bucks a box, 24-27 bucks a box, either way it costs you a couple lunches. It beats 30+ for a long action, not-06, and 35+ for a common magnum.
For reloaders time is generally worth more than cheap components, especially since there's only one place locally you can shoot non expanding bullets legally here. I only load one type of ammo for hunting, plinking, and targets.
As a game cartridge it will punch deep enough, and cause enough damage for a kill on anything we're likely to shoot at, from any angle, with any common loading. The cartridges larger than .243 can generally say the same (tho I've seen guys shooting pigs with fmj .308, or 06 "cause, stay cheap das why!" And wondering why they don't stay down), but smaller rounds, and the .243, can easily be found in ammo that's not effective. While the use of an fmj .223, or varmint bullet .22-250 or .243 loading is on the shooter/purchaser, you never hear that part of the story, all you hear is "shot em with_____ and it ran away!"
The low recoil, excellent accuracy that is generally experienced, and host of firearms it's available in, also generally lend it's self well to lunch table conversation.
This all sorta builds a reputation for the cartridge thats out of proportion to how much "better" it actually is, and here at least, word of mouth matters a great deal.
Again this is only what I'm seeing locally.
There's also plenty of folks who aren't interested, but they generally arnt buying new guns.