Keep in mind, that even with those loses, I believe the survival rates for the species have improved (though some nests might do badly more often than not). And keep in mind, we know when the birds die when they hit a stack, turbine, powerline, building, squirrel, but that is only a few relatively speaking to the number that die anonymously so to speak in their first year.
It is wonderful news from Xcel and well and truly above and beyond their responsibility to the birds at their plants. It is perfectly acceptable to project managers to say, "this site just won't work" and remove the nestbox for good. The peregrines are perfectly capable of finding somewhere new, with or without our assistance, though in cases like these, project managers tend to provide them with options nearby in order to retain successful pairs within an existing territory. Good for the birds, good for their fans and good for the project.