Had some Remington 257R brass on notification at Midway. Just got an email that it has been discontinued. Has anyone else heard of this? Is the brass discontinued at just Midway or has Remington quit making it?

Give Remington a call and see what they say. This way you are not listening to internet rumors and might get a straight answer.

It may or may not be discontinued. Some of these companies make special runs
of "less popular" rounds just once a year. My brother ran into this problem
after he inherited a .25-20, but eventually was able to get brass for it.

just take some 7x57r brass & run it through the sizer. google 7x57r brass & there's quite a bit out there