Willson Contreras
I told you things were getting interesting! Let me start by saying that I'm not suggesting this should happen, or telling you that it's in the Cardinals plans right now, but if you think about it, it could make a lot of sense.
Let me start by debunking something that you may be thinking - Willson Contreras is a great bat for a catcher, but first base is a different story. Wrong. He'd also been an excellent offensive first baseman. Don't believe me? Let's compare him to other first basemen offensively around the league.
Contreras' 127 wRC+ would have been fourth among all qualified first basemen in 2023, and while his counting stats may be lower than many of the top offensive first basemen, that has a lot to do with the fact he only got 428 at-bats in 2023 since he's a primary catcher. If you were to play Contreras at first base and get 150+ games a year from him rather than 120 or so games, you'd see him rack up even more home runs and runs batted in. You'd have to imagine he'd swing the bat better more often as well not squatting behind home plate for an entire season.
The emergence of Ivan Herrera plays a large role in this as well. If Herrera carries his strong 2023 campaign and electric offseason into the 2024 season, the Cardinals may want to explore ways for him to play more often. The easiest solution is having Contreras slot in at designated hitter more often, but if the first base job opens up, that can make a lot of sense too.
I could also see a world where Contreras plays a mixture of first base, catcher, and designated hitter in future years, allowing the Cardinals to mix and match their lineups throughout the season based on health and who the hot hands are. Again, I'm not making a prediction here, but Contreras would surely be a name to watch.