I don't know. As I said in another thread and got people upset who apparently didn't really understand my point, right now new film cameras are not, for the most part, being made (yesyes, there are a few, and plenty in large format) because the demand dropped so low relative to the available good used ones. If the demand stays constant or even increases, as the used ones dry up and die, there will come a time when they no longer meet the demand, and it would not surprise me to see new ones being made. This is true of mechanical cameras (that it wouldn't surprise me, not that it necessarily WILL happen) with 3D printing and rapid fabrication; it's likely even more true of slide projectors which are, when you get right down to it, very very simple devices. The Carousel isn't so simple mechanically but a simple projector can be built so easily, someone even half skilled could fabricate one at home. There's someone on here selling an LED lamphouse for Omega enlargers that he makes himself - I've bought one and it's nice. I bet he could make a slide projector too. Lenses for them can be assembled from off the self component elements and are essentially the same thing as used in digital projectors anyway.
I bet if they get rare and expensive used, we'll be able to buy new ones. Maybe not as nice as what we have/had, but they'll be functional.