Couldn't most textures have a lot of procedurally generated elements? That way you wouldn't need to store all the information.
Artists would just need to specify the procedural part, ie their editors would need to have that as well.
I think currently, the way artists work, they anyway have a lot of layers, and some of them are procedurally generated. I know people at least used to use something like "clouds" procedurally generated in Photoshop, and use that to apply some effects to the texture like wearing or staining. But in the end they "burn" the texture to bitmaps, and a lot less layers. Maybe that could be instead done on the GPU. Then the base texture becomes mostly flat, easily compressable, and the clouds can be procedurally generated, requiring no storage at all. It can still be deterministic, you can just store the seed.
That's essentially what PBR game engines do. They take in base textures/resources (NB: a "texture" doesn't necessarily correspond in any straightforward way to the final image, and shouldn't be thought of as an "image" except in the mathematical sense) and apply all sorts of processes to get a good looking final result.
Not everything can be procedurally generated on the fly (at least with a small algorithm that would run quickly enough on a GPU). At a certain point just providing compressed bitmaps becomes more efficient, especially since GPUs are highly specialised to work with exactly those. Everything is a tradeoff in real time graphics.
Artists would just need to specify the procedural part, ie their editors would need to have that as well.
I think currently, the way artists work, they anyway have a lot of layers, and some of them are procedurally generated. I know people at least used to use something like "clouds" procedurally generated in Photoshop, and use that to apply some effects to the texture like wearing or staining. But in the end they "burn" the texture to bitmaps, and a lot less layers. Maybe that could be instead done on the GPU. Then the base texture becomes mostly flat, easily compressable, and the clouds can be procedurally generated, requiring no storage at all. It can still be deterministic, you can just store the seed.