People don't project slides that much as we know, but I bet that if you make a slide projections (of good pictures) to some friends, many of them will tell you how nice it was to see slides projected again.
It's not that it is not feasible to make a slide from a digital image. It's that the technology doesn't entice people to project slides. Habits are changing. But they can change again.
If - hypothetically - a new technology could allow people to retain the good of digital (easy distributions, easy copying) with one aspect of the good of analogue (the "matter") and favoured the production of physical pictures, you would soon listen to people telling how nice it is, again, to pass pictures from hand to hand, or to see them on their purse.
So to make my point clearer, imagine a digital camera that allows people to instantly produce slides. At the moment, as we noticed, people don't project slides that much any more! But I think if they had a digital camera which makes "instant" slides of very good quality, that would certainly give a new impulse to the idea of slide projections. And I also think that, indirectly, that would give a new impulse to the sale of "analogue" slide film.