1. Alex Cora
Because the Cardinals are playing well right now, Oli Marmol has briefly been taken off the chopping block. He's done a much better job this season and still has the trust of the clubhouse. But if the Cardinals regress again and ultimately miss the playoffs, some changes could be considered, and another managerial option could emerge.
Depending on what happens with the Red Sox, Alex Cora, who led them to a title in 2018 could become available, and personally, I would love to see him manage the Cardinals. He actually briefly spent time in the organization in 2012 when they signed him to a minor league deal, so it's not like he doesn't have any Cardinals ties.
Of course, this won't and shouldn't be considered if the Cardinals make the playoffs and have a deep run. But Cora is another guy who would instantly have the respect of the clubhouse. He's also truly a player's manager, and in some ways reminds me of Mike Shildt. But I don't think this is out of the realm of possibility, especially if the Cardinals remain stuck in the middle.