I don't completely understand this thought either. If Hurts lays a big egg next week they can just go right back to Wentz. If Hurts plays well the point will be moot, but there is nothing that says that they can't play Wentz again.
On the other hand, if you're suggesting that Wentz is now guaranteed to leave at the end of the season, then maybe I get it. But is Wentz really good enough that he can absolutely refuse to take this on the chin? IIRC Wentz was criticized in the past for arrogance and selfishness (e.g.
https://www.bloggingtheboys.com/201...-view-carson-wentz-as-selfish-and-egotistical)
Also the entire NFL knows how bad his performance has been this season. It's not all his fault but even without playmakers around him he has been much worse than expected. Who will sign him and take on that contract? Someone will, but it's just as likely at this point that Wentz becomes another Kirk Cousins or Alex Smith which most people don't want.
This year, Mitch Trubisky was benched for Nick Foles for several games, and then he started again. Some would say he's not a franchise QB since he has no new contract. But he was a top two draft pick for whom the team traded away a ton of picks and was criticized for doing so.
There was also an aging Brett Favre, who was benched for Aaron Rodgers. It was of course, the right decision but Favre didn't accept it and went on to have two very good seasons with the Jets and Vikings. In that situation, the Packers couldn't go back to him. But Wentz is no Favre...and I wouldn't take him over Dak either.
IMO The Eagles gave him a huge contract on the basis of a Super Bowl that was really due to Nick Foles. It has backfired.