What I read is that US Steel doesn’t feel there’s a payback in investing in refurbishing the blast furnaces to keep them going, and want to move to other methods of steel production (apparently something called EAF is cheaper and more eco-friendly), and these would not be in Pittsburgh.

Nippon Steel OTOH still believes there is money in renovating and continuing to run the blast furnaces with the current staffing in place, so the unions who support the current workers are in favor of this.