Who are they likely to add?
As previously discussed, Winn is almost guaranteed to join the big league club in 2023. It's also likely that they'll add a pitcher. Rom could be added without having to DFA someone later, as he's on the 40-man roster. However, the Cardinals probably want to know what they have in a pitcher like McGreevy.
I do believe that both of these players will be added before the end of the season. Others with an outside shot at joining the 40-man roster are Nick Dunn, Adam Kloffenstein, and Gordon Graceffo. If these players are added, someone will be forced out, either in the short term or over the offseason.
However, by 2024, the Cardinals will need to add multiple players. This will certainly include Winn, and at least one or two internal pitching options. It will also (hopefully) include several external pitching options. If they come via trade, their spots could open organically, but if the pitching help comes via free agency, the Cardinals will have to make some difficult decisions. They'll probably add at least four to five players to the 40-man between now and Opening Day of the 2024 season.