I've been hearing about the death of .40 for decades. With all the .40s currently out there, I don't see the point in making new ones (unless there are LE departments out in rural areas that want the extra punch over 9mm), but the .40 is going to be around for a long time.
.357 Sig is just a hot 9mm and I'm not sure what extra effect it has on target that makes it worth the price. The bottleneck nature makes it very reliable for feeding, it's nice it can be converted to or from .40, but it's not like the extra velocity adds that much more to its effective range. Factory ammo is getting pricier for this every year and reloading it is more work, so I think it's dead.
.45 GAP is one that I've been thinking about recently. It shoots faster than .40 does with heavier bullets, but at the lighter end of loadings the .40 has better sectional density and I'd question if the hollow points for .45 GAP won't over expand and suffer from shallow penetration. I've also read that the heavy loadings can shoot inaccurately, but If the Glocks can shoot the 230gr well, then no problemo and I have read some people prefer shooting their .45 GAP to a Glock 21 or 30 because the grip is smaller.
The real drawback for .45 GAP is the low capacity. It's not more difficult to reload than any other straight wall case, so even if factory ammo is pricey that doesn't bother me. .45 GAP is the cheapest Glock you can buy used and every time I think about getting one I end up looking at used G21's and 30's and the prices for them are only 50-75 more and infinitely more resellable and hesitate. Doesn't help that the 38 is the GAP I'm most interested in and they're the least available.
.45 GAP has no signs of life, so it's even more dead than .357 Sig, but for reloaders calibers are like the multiverse in a Marvel movie- nothing/nobody is ever really dead and the .45 GAP is an easy monster for Dr. Reloaderstein to bring back to life.
