1. You're only going to see so much details, so making bigger textures will not make much sense soon. We're already at the level where the art design / mapping / movement / realistic lighting could improve the situation much more than extra resolution. Games can already run at up to 4k and virtually nobody even has hardware for it.
2. There's only so much bandwidth on the storage - graphics memory and graphics memory - GPU lines. If you can't realistically process the textures/geometry you want to display, there's no point making it.
1PB drives will come though for long term storage. We already have petabytes of data being processed in some companies. It's just a question of $/B ratio, whether the R/W speed is reasonable for that size, and how reliable do you want that storage to be.
However for other applications it's not the same thing. I work in medical 3D imaging - we are constantly memory constrained.