Reason #2 - The Cardinals would not get enough in return to make a Paul Goldschmidt trade worth it
It's hard to find fair comparisons to a potential Goldschmidt trade due to his unique situation as a reigning MVP who is in his mid-30s and still playing at an All-Star level. So let's look at the return of an All-Star first baseman that was dealt two offseasons ago, Matt Olson.
Olson was traded to the Braves for prospects C Shea Langeliers, OF Christan Pache, RHP Ryan Cusick, and RHP Joey Estes. Langeliers was the 73rd-ranked prospect in baseball, Pache was a former top prospect but had fallen a ton in his status among talent evaluators, while Cusick and Estes ranked 16th and 26th in the Athletics own farm system upon their acquisition.
Olson wasn't coming off an MVP season, but he did post a .911 OPS for the Athletics the prior season, was an All-Star, finished 8th in MVP voting, and was only 27 years old and had two years left of club control before he hit free agency. That's a very valuable player, and that's the return the A's got back for him.
That doesn't mean the Cardinals couldn't get more for Goldschmidt, but coming up on his 36th birthday and being a year away from free agency, it doesn't feel like the package in return would be much better than the Athletics got for Olson. So is that really going to entice the Cardinals to give up Goldschmidt?
Some would say "Well, trade him for an established ace then", but no team trading for Goldschmidt is going to do that. If a team is interested in him at the deadline, they are contenders. Contenders will part with prospects and fringe MLB talent, but they aren't going to give up a front-line starter to acquire a bat. That's just not how teams operate.
Beyond 2023, there are plenty of reasons for the Cardinals to hold onto Goldschmidt.