I thought what was really desired was to get all your rookies promoted at roughly the same time so they can grow together (see 1982 Twins).
They clearly aren't going to add anyone to the roster who isn't absolutely required to be added to the roster. As far as I know the only AAA prospects who absolutely have to be added to avoid being selected in Rule 5 are Jose Miranda, Joe Ryan and Jovani Moran. Right now I am betting they all finish out the AAA schedule but those are your only possible roster adds between now and November who are actual prospects.
With the Maeda injury the front office might be ready to tear this team down and trade everyone with 2 or fewer years of team control (Donaldson, Sano, Garver, Taylor Rogers, Tyler Duffey and Buxton).