depends
Depends on your definition of "dead".
We will continue to have the ammo, or at least I hope we will, along with all our other calibers, short of political catastrophy. They're are enough M1 carbines, surplus, import and repro, as well as the smattering of hanguns, to sustain production. And I note that their is a "new" manufacturer of carbines, to compete with the Kahr, so that makes two.
But you will not see any other firearms, aside from the repros and maybe Rugers revolver (do they even still make the B-hawk in .30?) in the Carbine cartridge. The 7.62x39, the .223, the .300 Blk, the rampant AR and the previous glut of AK clones, pretty much can do what the Carbine does, and more, without a lot of compromise, the weight issue being the most noteable.
Historically, the .30 Carbine cartridge, seemed to surface out of nowhere. The .351 Win and the thumping .401 already existed and were improvements over the previous weaker SLR cartridges, noteably the .32 SLR. We've debated it before, but why the .30 Carbine surfaced ahead of these existing rounds still seems odd to me. It did, and there it is, but....I still don't get it.
I've shot a lot of the .30 M1 Carbine, once, upon a time. I'll spare the fine points, but I enjoyed it greatly, and have always wanted one. But at four figures for a repro, it's likely not gonna happen.