Nobody is concerned about the quantity of land used by an active datacenter.

Local municipalities are having to upgrade municipal infrastructure as a result of these projects -- which wouldn't be too bad, if they can be guaranteed the tax revenue to pay for those things -- and the employer sticks around and maintains their property.

But in a bubble, it is foreseeable that many of these properties will go under when the bubble pops, and local municipalities will be left footing the bill without the tax revenue.