So this is my area of practice, and obviously I'm coming from the legal side but I know enough of the business side to be dangerous.
If the build out is done correctly, residential customers shouldn't be hurt. They could even benefit since the data centers will cover proportionally more of the fixed costs as heavy users.
Since I know Iowa the best, part of the reason for the growth is the huge amount of wind energy already being generated thanks to the Berkshire affiliate who has acted more like a tax credit farm than a regulated utility for the last 25 years. I'm not a huge fan of some of their tactics, but they should be able to absorb a lot of data center growth provided they can get more generation in the pipeline (which the current federal government is not exactly helping with).