Allowing unbridled data centers will absolutely explode retail electricity prices for normal Americans ... and rather obviously the energy to power these data centers must come from somewhere, and right now fossil fuels are the main source, which just compounds global warming. Perhaps politicians should stop taking bribes and demand that all these data centers be energized by 100% solar and wind ? Zuck chose Louisiana, a fossil fuel rich state that is well known for bribery and located his data center in a poor rural area.
The obvious solution here (besides, like you say, requiring datacenter electricity to be from 100% renewable sources) is to just charge datacenters more for electricity, such that they offset their impact on demand. That's exactly what my state's energy company (NV Energy) has been trying to do with so-called “large-load electrical service agreements” (LLESAs).
It's not so absolute. In the first order, yes, if you don't grow generation or transmission, it has to increase prices. But in the second order, those things happen, and the end result can be lower prices on scale.
That leaves it up to chance, and the timing would lag, so the simpler solution is as @yellowapple says, have the data centers pay for the new transmission and generation, which takes chance out of the equation and ensures retail prices decline (unless someone mismanages the whole grid in the future).
