This doesn't sound right, it's very doubtful that all storage tech has royalty (unit-based) license terms.

Instead of electricity consumption the limiting factor will be raw materials to manufacture storage. Likely even worse for the environment given the energy and raw material cost to manufacture storage devices.

I was more thinking of the waste involved in manufacturing. If there's suddenly a much more direct profit motive to buying drives it's going to push more manufacturing, which is not the same as ongoing burning of energy for PoW, sure, but it's not going to be without side effects.

overall it would be significantly less, that is the point

I'm not convinced it would.

Just like PoW it makes sense to spend enough until a breakeven point. In thise case there is a direct incentive to buy as much storage as possible.