while i dont think zeke's talent is easily replaceable (i do think he's a top 3 or top 5 back in the league), i think it's pretty redundant to pay huge money to your entire OL while also paying huge money for the back.
the cowboys are projected to have a healthy amount of cap space next summer, but on top of paying dak and cooper, they have some other pending FA's like byron jones, bennett/quinn, jeff heath (he's not very good, but is still a starter).
if they want to re-up dak and cooper, they're not going to be able to substantially upgrade via FA, so just roll with what they have and hope draft picks pan out