They won't even last that long. In the Sept. 2004 Guns & Ammo, Craig Boddington did an article on the .223 WSSM and said that the rifle Hornady used in testing had throat erosion after only 350 rounds. The shape of the cartridge itself is going to lend itself to feeding issues. I think a lot of these short fat wonders are going to fade away. The Remington SAUM's are all but dead now. These cartridges don't bring anything new to the table except being avaliable in a short action, which in itself offers zero advantage. Some will fill a nitche, but most will go away in time. Too many new calibers introduced too quickly. The gun market can only absorb just so much. Bill T.WSSM barrels last 750 to 1000 rounds at the most. i had a mini 14 that had over 10,000 rounds through it. No brainer.
You forgot Mosin Nagant owners... with ammo as cheap as 880 rounds for $114, shipped, it's pretty easy to blow through 1000 in a year. One would only need to use 40 rounds each week for 40 weeks (52 weeks in a year) and you're already at 1600 rounds; and that's with the 7.62x54R.outside of prarie dog shooters, most hunters never put a 1000rnds through a rifle in a lifetime