Of course this is just a theoretical exercise. Technically, there's nothing in a QR code's algorithm or the mathematics that prevents it from scaling infinitely. The error correction algorithm even allows up to 30% of the code to be damaged and still retrieve the data.

Practically though.. Well, given the QR code is smaller than bacteria, paper looks more like a tangled forrest of plant fibers at that scale. Paper just doesn't support that kind of resolution.

However, I'm inclined to believe humanity can print that QR code on silicon wafers like we do with chips.