My biggest problem with all the new "wunderrounds" is two fold, one is, is their level of performance worth the cost to me, today, and the other is a bit bigger concern, where are these rounds going to be down the road 5 years, 10? more??
The list of adequate, and even excellent performing rounds being dropped by their makers because they don't sell enough of them is long. And when the now "obsolete" cases cannot be made from common and still available brass, what are you going to do with what's now an expensive and rare niche round?
And the rifle that shoots it??
Unless its some kind of collector's item, generally speaking the value of a gun for which there is no ammunition is quite low. SO....
IF the ammo maker's drop the round, we're stuck with what we can grab out of the existing supply before every other owner of the same thing does the same thing, and when that's used up, we've got a rifle we can't use and one no body else wants, because they can't use it, either.
SOME discontinued rounds can be made from still thriving rounds cases. Some cannot be. I've got a .350 Rem Mag. Ammo and brass is really scarce, HOWEVER, since it uses the same head & belt as other thriving magnum rounds, I can make brass for it, when I need to.
If you get a proprietaryA fat bodycase with a head rebated to 06 size, where are you going to find brass to make it out of, IF sales slump and the big makers drop it?
There are other examples its just kind of a crap shoot IF one of the new rounds will last on the commercial market, or not.
I am always mindful of the story of the 5mm Rem Mag. It was they hot new rimfire when it came out, pretty popular when it came out, but after a few years, interest waned, and after that Remington dropped the rifle. And a few years after that, they dropped the ammo, as well.
Being the only maker for the ammo, and it being a proprietary round (and a rimfire, to boot) there was nothing else one could make ammo from.
A decade or so later, you could buy a 5mm Rem rifle for less money than the cost of a single box of 5mm Rem Mag ammo, IF you could even find a box for sale.
The really smart course is to get a lifetime supply of ammo/brass when you get the new rifle. It adds to the up front cost considerably, of course, but consider that if the round survives commercially, you would be buying that ammo/brass anyway (though in smaller batches over time) and it it doesn't you'll have enough for your personal use, or enough to sell with the rifle (if/when) to make it attractive to someone...