A lot of the newer stuff has better ballistics etc than the older cartridges. But a lot of the "new stuff" will die out just because of the amount of "older guns" out there already that take the "standard cartridges" that are readily available and more economical.

Even if they never built another one there are way more 30-06, 30-30 etc out there now used than there will ever be of say new 300 BO or others made.

Most people arent very quick to go drop $500+ on a new rifle/caliber just because its a little faster/flatter shooting when the old 30-06, 270,30-30 etc they already have kills things just fine and ammo is plentiful and cheaper.

Sorry. But I strongly disagree. Most people ARE will to drop 500 or more on a new caliber!!!!! IT they were not why would thy be so many new calibers coming out???? People always want more! Its a fact!! They wouldnt be building them if people didnt want them!!! Its marketing at its finest. They convence you = most people that their new rifle / cartridge is better! If this where not true . WHY would they be advertizing tje 26 Nosler = then the 28 Nosler. WAKE UP!!! Someone is dropping lots more than 500 dollars for new rifles!

If ya look I said $ 500 +. I agree its marketing at its finest. Wasnt it P.T. Barnum who said "a sucker is born every minute".
Im not saying that they arent sold, or that a lot of them are not much ballistically superior than some that have been around for many many years.
But, the "average" shooter/hunter/person on this forum has never heard of a 26 or 28 Nosler or most of the other newer calibers much less even seen one.
True there are a lot of neophiliac , range hounds , and handloaders who will buy into the latest and greatest but how well are they going to stick around and be on the shelf as the OP originally asked?

You will have a few that will survive. But I would bet ya a steak dinner if you took all the new calibers out in the past 10 years that 20 years from now you will not be able to find 95% of them commercially while the "old standards" are still on the shelves and new firearms still being built in those calibers.

People already complain now and steer people away from the "hard to find" 7mm~08 which has steadily climbed in popularity and to me never has been hard to find and shouldn't be to anyone who can read these words.

On the opposite end ya have the 35 Remington. With as many thousands and thousands of leverguns that were made for it for many years and its many followers reloading components are almost nil and factory ammo is limited to one or maybe two runs a year.

The 25 WSSM the OP mentions is only a 11 yr old cartridge and already cant find brass for it.

I still stick by the majority of them may be better than old but most will die commercially or the components will be too expensive and obscure to continue.

yeah I got sucked into the 260 versus 6.5 Creedmoor battle so I bought both. lol I can't find a load the Creedmoor likes yet but the 260 impressed me right off the bat so it's gotten more attention.

There is no doubt that I do not need another gun of any caliber so when I buy one it's simply because I just want to play with it however when I go hunting I usually grab the old reliable/trusty 25-06 and sometimes the 308 Savage Hog Hunter. For the money I absolutely love that rifle.