Let's assume he does hold out, what are the Cowboys options at that point?
They can rescind the tag; however, that tag is considered used for that season so they couldn't use it on Cooper or Jones. Until the tender is signed, it can be withdrawn.
So, what would you do? Got a new HC that you specifically hired to take the team up, not level and then up.
What we really don't know is how much does Big Mike love him some Prescott? Is it a "get him camp, whatever you need to do" or a "let's look at the other QB's that might be available"?
The tricky part is the waiting game. What is the drop dead date for Big Mike to have his QB? What other QB's might be available at that time?
Feb 3, the waiver system kicks in.
Feb 25, players can be tagged
Mar 16, teams can begun contract talks with their UFA's with contracts expired in 2019
See a problem here?
Let's say Rivers hits the open market but the Cowboys are still trying to make a deal with Prescott and they don't have a feel for if he will hold out or not.
The more I think about this, and believe me I am tired of thinking about it, it's a simple either or. If he's your guy, do the best deal you can and move on, no tag. If you are even considering the tag, let him go find another team, get the best FA QB and draft one in the 1st this draft and the next one as well, if necessary. Playing the tag game with a QB that they're not sure of what he will do is wasting time. Time that they do not have as much as they think they do.
And there's one thing in their favor about this, any QB is going to have to learn this offense, Prescott does not hold an edge and any QB that's played more of a WCO does. This would be the time to let him walk.