Scenario #2: High prospects, high dollars
This scenario isn't as likely as a mix between dollars and prospects, but it is probably more likely than the first scenario. Here, the Cardinals receive plenty of money to offset Trout's massive contract. In this scenario, it is possible the Cardinals receive up to $120 million in exchange from the Angels. That would cover about half of his remaining salary. That is a pretty penny for the Angels to pay, but it provides the Cardinals with financial flexibility, and it doesn't hamper the front office's free agency plans too much.
The issue with this scenario would be the players the Cardinals would have to send back. Surely, the Angels would be asking for quite the package if they are making Mike Trout a $17.5 million player a year. It would be reasonable for Los Angeles to ask for AT LEAST one of Jordan Walker, Masyn Winn, Tink Hence, and Nolan Gorman. Additionally, the Cardinals would probably have to send over Zach Thompson or Matthew Liberatore, and other major league players such as Dylan Carlson, Tommy Edman, Lars Nootbaar, or Brendan Donovan.
While losing a top prospect, a lower-end starter and a heavy contributor to the major league roster would hurt the Cardinals, getting a middle-of-the-order bat for the next 7 years would help offset that pain. Also, the Cardinals would maintain financial flexibility to fill in the rotation and depth spots. While this isn't an ideal trade, it is certainly a possibility.