I think the hope is for Trey Lance to substantially improve this coming season, so that he can be ready to replace Cooper Rush as the team's primary back-up QB in 2024. If he does so, that gives the Cowboys some more options. If he doesn't, well they took a chance that didn't work out. In any case, Dak will be the starter at least through the end of his current contract.
The Cowboys could choose to eat the entire $59M CAP hit in 2024 by keeping CeeDee on his fifth year option, and exercising their 5th year option on Parsons for 2025. So, the real pinch comes in 2025, not 2024. By that time, the Cowboys can move on from players like Demarcus Lawrence and Tyron Smith. They also might move on from Zack Martin, if he chooses to retire.
I think the real window is 2 seasons for the veterans Dak, Zack, Tyron, and Lawrence. The Cowboys have young pieces potentially in place to replace Tyron and Lawrence now with Tyler Smith/Asim Richards, and Sam Williams. They potentially have a replacement for Zack in T.J. Bass. They can also move on from Leighton Vander Esch in 2025 if Overshown and Clark show up big in the next two years.
They have an issue at Center, because they likely cannot afford to keep Tyler Biadasz in 2024. They need a replacements after 2023 for Gilmore and Pollard, and after 2024 for a bunch of veterans, if they choose to move on from them, so that they can keep their young stars CeeDee and Micah.
Hence the lottery ticket bought on Trey Lance in the trade a couple of weeks ago. It is a longshot, as all lottery tickets are. But the Cowboys are preparing to move on from all key players on the roster that were selected prior to the the McCarthy era. Of course they'd like to keep veteran players, if possible. But not at the cost of retaining the young rising stars on the team.