I don't think Barrett is going to create a new action for a limited run. Short or long action standard rounds. Anything larger or smaller probably isn't in the cards. Don't think a left hand action is coming out for a limited run either.
They could keep their short action and add a mag face bolt for the SAUM... Actually would work quite well as their mag box is longer than a standard Rem 700 SA....
“There are some who can live without wild things and some who cannot.” ALDO LEOPOLD