On Saturday, the Royals can begin expanding rosters and calling up players from the minors to invite them on this sinking ship of a season. You can read all you need to know about September callups here. The minor league seasons for Omaha and Northwest Arkansas ends on Monday, September 3, so you may not see some callups until after they have concluded their seasons.
Who gets called up will depend upon a few things, minor league performance, whether or not the club feels the player can handle a promotion at this time, and 40-man roster considerations.