Actually, I think that Cooper's success as Dak's backup is relevant to Trey's ability to revive his career.
Trey Lance's career is in serious need of development. Currently, he doesn't have the experience and tools to be a successful starter in the NFL. He needs two years of learning behind Dak in the same way that Tony Romo did. I think that would give him a serious opportunity to be better prepared to face NFL defenses.
In order for that to happen, somebody else has to be available to play in the event Dak cannot. Cooper is that guy. However, if he cannot replicate his success of 2022 then that could force the Cowboys to put Trey in before he is ready. We have seen time and time again, how forcing in a developmental player destroys the entire process.
We often hear about players being "developmental" but that rarely happens. It did happen with Tony Romo and we saw the positive results. Hopefully they can do the same with Trey who I feel has a greater potential given his physical abilities.