You can't actually substitute something with nothing, and conservation laws (of mass, energy, etc) do hold. But in practice, substituting with, say, atmosphere,

You can't actually substitute something with nothing, and conservation laws (of mass, energy, etc) do hold. But in practice, substituting with, say, atmosphere, is almost as good. OP discussed the case of substituting copper network with atmospheric spectrum. Consider guano: guano use for manufacturing fertilizer is down, because Harber-Bosch process substituted guano nitrogen with atmospheric nitrogen. Atmospheric nitrogen is still a material thing, but it sure does look like dematerialization.